我已经完成rvm remove了 Ruby，但宝石仍然存在：
$ rvm remove ruby-1.8.7-head
Removing /Users/agrimm/.rvm/src/ruby-1.8.7-head...
Removing /Users/agrimm/.rvm/rubies/ruby-1.8.7-head...
Removing ruby-1.8.7-head aliases...
Removing ruby-1.8.7-head wrappers...
Removing ruby-1.8.7-head environments...
Removing ruby-1.8.7-head binaries...
$ ls /Users/agrimm/.rvm/gems | grep 1.8.7
ruby-1.8.7-head
ruby-1.8.7-head@global
我这样做是因为我想进行一次失败的 gem 安装尝试，但是传统的尝试失败了：
$ gem install pkg/laser-0.7.0.pre2.gem
Fetching: ripper-plus-1.3.0.gem (100%)
Fetching: axiom_of_choice-1.0.0.gem (100%)
Fetching: stream-0.5.gem (100%)
Fetching: object_regex-1.0.1.gem (100%)
Fetching: trollop-1.16.2.gem (100%)
Building native extensions. This could take a while...
Successfully installed ripper-plus-1.3.0
Successfully installed axiom_of_choice-1.0.0
Successfully installed stream-0.5
Successfully installed object_regex-1.0.1
Successfully installed trollop-1.16.2
Successfully installed laser-0.7.0.pre2
6 gems installed
dyld: lazy symbol binding failed: Symbol not found: _capi_get_constant
Referenced from: /Users/agrimm/.rvm/gems/ruby-1.8.7-head/gems/json-1.7.1/lib/json/ext/parser.bundle
Expected in: flat namespace
dyld: Symbol not found: _capi_get_constant
Referenced from: /Users/agrimm/.rvm/gems/ruby-1.8.7-head/gems/json-1.7.1/lib/json/ext/parser.bundle
Expected in: flat namespace
f8-1e-df-dc-3b-2a:laser agrimm$ gem install pkg/laser-0.7.0.pre2.gem
Invalid gemspec in [/Users/agrimm/.rvm/gems/ruby-1.8.7-head/specifications/laser-0.7.0.pre2.gemspec]: Illformed requirement ["#<YAML::Syck::DefaultKey:0x1046be400> 0.5"]
Invalid gemspec in [/Users/agrimm/.rvm/gems/ruby-1.8.7-head/specifications/laser-0.7.0.pre2.gemspec]: Illformed requirement ["#<YAML::Syck::DefaultKey:0x1046be400> 0.5"]
Building native extensions. This could take a while...
Successfully installed laser-0.7.0.pre2
1 gem installed
dyld: lazy symbol binding failed: Symbol not found: _capi_get_constant
Referenced from: /Users/agrimm/.rvm/gems/ruby-1.8.7-head/gems/json-1.7.1/lib/json/ext/parser.bundle
Expected in: flat namespace
dyld: Symbol not found: _capi_get_constant
Referenced from: /Users/agrimm/.rvm/gems/ruby-1.8.7-head/gems/json-1.7.1/lib/json/ext/parser.bundle
Expected in: flat namespace
$ gem list laser
Invalid gemspec in [/Users/agrimm/.rvm/gems/ruby-1.8.7-head/specifications/laser-0.7.0.pre2.gemspec]: Illformed requirement ["#<YAML::Syck::DefaultKey:0x104eb6838> 0.5"]
*** LOCAL GEMS ***
Invalid gemspec in [/Users/agrimm/.rvm/gems/ruby-1.8.7-head/specifications/laser-0.7.0.pre2.gemspec]: Illformed requirement ["#<YAML::Syck::DefaultKey:0x104eb6838> 0.5"]
$ gem uninstall laser
Invalid gemspec in [/Users/agrimm/.rvm/gems/ruby-1.8.7-head/specifications/laser-0.7.0.pre2.gemspec]: Illformed requirement ["#<YAML::Syck::DefaultKey:0x104eb6838> 0.5"]
Invalid gemspec in [/Users/agrimm/.rvm/gems/ruby-1.8.7-head/specifications/laser-0.7.0.pre2.gemspec]: Illformed requirement ["#<YAML::Syck::DefaultKey:0x104eb6838> 0.5"]
ERROR: While executing gem ... (Gem::InstallError)
cannot uninstall, check `gem list -d laser`
$ gem list -d laser
Invalid gemspec in [/Users/agrimm/.rvm/gems/ruby-1.8.7-head/specifications/laser-0.7.0.pre2.gemspec]: Illformed requirement ["#<YAML::Syck::DefaultKey:0x104eb6838> 0.5"]
*** LOCAL GEMS ***
Invalid gemspec in [/Users/agrimm/.rvm/gems/ruby-1.8.7-head/specifications/laser-0.7.0.pre2.gemspec]: Illformed requirement ["#<YAML::Syck::DefaultKey:0x104eb6838> 0.5"]
$