我正在尝试为客户的项目进行构建，但我遇到了太多错误。
bundle exec middleman build
/Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/middleman-sprockets-3.1.2/lib/middleman-sprockets/sass_function_hack.rb:18:in `image_url': undefined local variable or method `sprockets_context' for #<Sass::Script::Functions::EvaluationContext:0x007fd75de5efe8> (NameError)
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/sass-3.2.9/lib/sass/script/funcall.rb:112:in `_perform'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/sass-3.2.9/lib/sass/script/node.rb:40:in `perform'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/sass-3.2.9/lib/sass/tree/visitors/perform.rb:298:in `visit_prop'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/sass-3.2.9/lib/sass/tree/visitors/base.rb:37:in `visit'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/sass-3.2.9/lib/sass/tree/visitors/perform.rb:100:in `visit'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/sass-3.2.9/lib/sass/tree/visitors/base.rb:53:in `block in visit_children'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/sass-3.2.9/lib/sass/tree/visitors/base.rb:53:in `map'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/sass-3.2.9/lib/sass/tree/visitors/base.rb:53:in `visit_children'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/sass-3.2.9/lib/sass/tree/visitors/perform.rb:109:in `block in visit_children'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/sass-3.2.9/lib/sass/tree/visitors/perform.rb:121:in `with_environment'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/sass-3.2.9/lib/sass/tree/visitors/perform.rb:108:in `visit_children'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/sass-3.2.9/lib/sass/tree/visitors/base.rb:37:in `block in visit'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/sass-3.2.9/lib/sass/tree/visitors/perform.rb:320:in `visit_rule'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/sass-3.2.9/lib/sass/tree/visitors/base.rb:37:in `visit'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/sass-3.2.9/lib/sass/tree/visitors/perform.rb:100:in `visit'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/sass-3.2.9/lib/sass/tree/visitors/base.rb:53:in `block in visit_children'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/sass-3.2.9/lib/sass/tree/visitors/base.rb:53:in `map'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/sass-3.2.9/lib/sass/tree/visitors/base.rb:53:in `visit_children'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/sass-3.2.9/lib/sass/tree/visitors/perform.rb:109:in `block in visit_children'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/sass-3.2.9/lib/sass/tree/visitors/perform.rb:121:in `with_environment'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/sass-3.2.9/lib/sass/tree/visitors/perform.rb:108:in `visit_children'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/sass-3.2.9/lib/sass/tree/visitors/base.rb:37:in `block in visit'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/sass-3.2.9/lib/sass/tree/visitors/perform.rb:128:in `visit_root'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/sass-3.2.9/lib/sass/tree/visitors/base.rb:37:in `visit'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/sass-3.2.9/lib/sass/tree/visitors/perform.rb:100:in `visit'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/sass-3.2.9/lib/sass/tree/visitors/perform.rb:7:in `visit'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/sass-3.2.9/lib/sass/tree/root_node.rb:20:in `render'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/sass-3.2.9/lib/sass/engine.rb:315:in `_render'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/sass-3.2.9/lib/sass/engine.rb:262:in `render'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/middleman-core-3.0.14/lib/middleman-core/renderers/sass.rb:67:in `evaluate'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/tilt-1.3.7/lib/tilt/template.rb:77:in `render'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/middleman-core-3.0.14/lib/middleman-core/core_extensions/rendering.rb:264:in `render_individual_file'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/middleman-core-3.0.14/lib/middleman-core/core_extensions/rendering.rb:148:in `render_template'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/middleman-core-3.0.14/lib/middleman-core/sitemap/resource.rb:128:in `block in render'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/activesupport-3.2.13/lib/active_support/notifications.rb:125:in `instrument'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/middleman-core-3.0.14/lib/middleman-core/util.rb:60:in `instrument'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/middleman-core-3.0.14/lib/middleman-core/application.rb:222:in `instrument'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/middleman-core-3.0.14/lib/middleman-core/sitemap/resource.rb:14:in `instrument'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/middleman-core-3.0.14/lib/middleman-core/sitemap/resource.rb:114:in `render'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/middleman-core-3.0.14/lib/middleman-core/core_extensions/request.rb:255:in `process_request'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/middleman-core-3.0.14/lib/middleman-core/core_extensions/request.rb:204:in `block in call!'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/middleman-core-3.0.14/lib/middleman-core/core_extensions/request.rb:203:in `catch'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/middleman-core-3.0.14/lib/middleman-core/core_extensions/request.rb:203:in `call!'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/middleman-core-3.0.14/lib/middleman-core/core_extensions/request.rb:188:in `call'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/rack-1.4.5/lib/rack/builder.rb:134:in `call'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/rack-1.4.5/lib/rack/urlmap.rb:64:in `block in call'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/rack-1.4.5/lib/rack/urlmap.rb:49:in `each'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/rack-1.4.5/lib/rack/urlmap.rb:49:in `call'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/rack-1.4.5/lib/rack/builder.rb:134:in `call'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/rack-test-0.6.2/lib/rack/mock_session.rb:30:in `request'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/rack-test-0.6.2/lib/rack/test.rb:230:in `process_request'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/rack-test-0.6.2/lib/rack/test.rb:57:in `get'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/middleman-core-3.0.14/lib/middleman-core/cli/build.rb:259:in `block in execute!'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/middleman-core-3.0.14/lib/middleman-core/cli/build.rb:256:in `each'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/middleman-core-3.0.14/lib/middleman-core/cli/build.rb:256:in `execute!'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/middleman-core-3.0.14/lib/middleman-core/cli/build.rb:198:in `invoke!'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/thor-0.15.4/lib/thor/actions.rb:95:in `action'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/middleman-core-3.0.14/lib/middleman-core/cli/build.rb:65:in `build'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/thor-0.15.4/lib/thor/task.rb:27:in `run'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/thor-0.15.4/lib/thor/invocation.rb:120:in `invoke_task'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/thor-0.15.4/lib/thor.rb:275:in `dispatch'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/thor-0.15.4/lib/thor/base.rb:425:in `start'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/middleman-core-3.0.14/lib/middleman-core/cli.rb:77:in `method_missing'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/thor-0.15.4/lib/thor/task.rb:29:in `run'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/thor-0.15.4/lib/thor/task.rb:126:in `run'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/thor-0.15.4/lib/thor/invocation.rb:120:in `invoke_task'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/thor-0.15.4/lib/thor.rb:275:in `dispatch'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/thor-0.15.4/lib/thor/base.rb:425:in `start'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/middleman-core-3.0.14/lib/middleman-core/cli.rb:22:in `start'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/gems/middleman-core-3.0.14/bin/middleman:18:in `<top (required)>'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/bin/middleman:23:in `load'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/bin/middleman:23:in `<main>'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/bin/ruby_noexec_wrapper:14:in `eval'
from /Users/mbp-gomes/.rvm/gems/ruby-1.9.3-p448/bin/ruby_noexec_wrapper:14:in `<main>'
有什么有用的信息吗？
RUBY：ruby 1.9.3p448（2013-06-27 修订版 41675）[x86_64-darwin12.4.0] RAILS：Rails 4.0.0
宝石清单：
actionmailer (4.0.0, 2.3.18)
actionpack (4.0.0, 2.3.18)
activemodel (4.0.0)
activerecord (4.0.0, 2.3.18)
activerecord-deprecated_finders (1.0.3)
activeresource (2.3.18)
activesupport (4.0.0, 3.2.13, 2.3.18)
arel (4.0.0)
atomic (1.1.10)
bigdecimal (1.1.0)
bootstrap-sass (2.3.2.1)
builder (3.1.4)
bundler (1.3.5)
bundler-unload (1.0.1)
chunky_png (1.2.8)
coffee-script (2.2.0)
coffee-script-source (1.3.3)
compass (0.12.2)
erubis (2.7.0)
execjs (1.4.0)
ffi (1.9.0)
fssm (0.2.10)
haml (4.0.3)
hike (1.2.3)
http_router (0.10.2)
i18n (0.6.4, 0.6.1)
io-console (0.3)
json (1.5.5)
listen (1.2.2, 0.7.3)
mail (2.5.4)
maruku (0.6.1)
middleman (3.0.14)
middleman-core (3.0.14)
middleman-more (3.0.14)
middleman-sprockets (3.1.2)
mime-types (1.23)
minitest (4.7.5, 2.5.1)
multi_json (1.7.7)
padrino-core (0.10.7)
padrino-helpers (0.10.7)
polyglot (0.3.3)
rack (1.5.2, 1.4.5, 1.1.6)
rack-protection (1.5.0)
rack-test (0.6.2)
rails (4.0.0, 2.3.18)
railties (4.0.0)
rake (10.1.0, 0.9.2.2)
rb-fsevent (0.9.3)
rb-inotify (0.9.0)
rb-kqueue (0.2.0)
rdoc (3.9.5)
rubygems-bundler (1.2.2)
rvm (1.11.3.8)
sass (3.2.9)
sinatra (1.3.6)
sprockets (2.10.0)
sprockets-helpers (1.0.1)
sprockets-rails (2.0.0)
sprockets-sass (1.0.1)
syntax (1.0.0)
thor (0.18.1, 0.15.4)
thread_safe (0.1.0)
tilt (1.4.1, 1.3.7)
treetop (1.4.14)
tzinfo (0.3.37)
uglifier (1.2.7)
url_mount (0.2.1)
提前致谢！
最好的