我正在尝试安装gpg-agent，但我收到一个公式不存在的错误：
$ brew install gpg-agent
Error: No available formula with the name "gpg-agent"
==> Searching for a previously deleted formula (in the last month)...
Warning: homebrew/core is shallow clone. To get complete history run:
git -C "$(brew --repo homebrew/core)" fetch --unshallow
Error: No previously deleted formula found.
==> Searching for similarly named formulae...
Error: No similarly named formulae found.
==> Searching taps...
==> Searching taps on GitHub...
Error: No formulae found in taps.
但是，这个公式似乎仍然有效：https ://formulae.brew.sh/formula/gpg-agent
有什么我配置不正确的吗？其他公式按预期工作（例如brew install gpg，brew install pinentry-mac）。
如果此信息有帮助：
$ brew doctor
Please note that these warnings are just used to help the Homebrew maintainers
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Warning: Unbrewed dylibs were found in /usr/local/lib.
If you didn't put them there on purpose they could cause problems when
building Homebrew formulae, and may need to be deleted.
Unexpected dylibs:
/usr/local/lib/libtcl8.6.dylib
/usr/local/lib/libtk8.6.dylib
Warning: Unbrewed header files were found in /usr/local/include.
If you didn't put them there on purpose they could cause problems when
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Unexpected header files:
/usr/local/include/fakemysql.h
/usr/local/include/fakepq.h
/usr/local/include/fakesql.h
/usr/local/include/itcl.h
/usr/local/include/itcl2TclOO.h
/usr/local/include/itclDecls.h
/usr/local/include/itclInt.h
/usr/local/include/itclIntDecls.h
/usr/local/include/itclMigrate2TclCore.h
/usr/local/include/itclTclIntStubsFcn.h
/usr/local/include/mysqlStubs.h
/usr/local/include/odbcStubs.h
/usr/local/include/pqStubs.h
/usr/local/include/tcl.h
/usr/local/include/tclDecls.h
/usr/local/include/tclOO.h
/usr/local/include/tclOODecls.h
/usr/local/include/tclPlatDecls.h
/usr/local/include/tclThread.h
/usr/local/include/tclTomMath.h
/usr/local/include/tclTomMathDecls.h
/usr/local/include/tdbc.h
/usr/local/include/tdbcDecls.h
/usr/local/include/tdbcInt.h
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/usr/local/include/tkDecls.h
/usr/local/include/tkPlatDecls.h
Warning: Unbrewed .pc files were found in /usr/local/lib/pkgconfig.
If you didn't put them there on purpose they could cause problems when
building Homebrew formulae, and may need to be deleted.
Unexpected .pc files:
/usr/local/lib/pkgconfig/tcl.pc
/usr/local/lib/pkgconfig/tk.pc
Warning: Unbrewed static libraries were found in /usr/local/lib.
If you didn't put them there on purpose they could cause problems when
building Homebrew formulae, and may need to be deleted.
Unexpected static libraries:
/usr/local/lib/libtclstub8.6.a
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Warning: You have unlinked kegs in your Cellar
Leaving kegs unlinked can lead to build-trouble and cause brews that depend on
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nmap
Warning: Homebrew's sbin was not found in your PATH but you have installed
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Consider setting the PATH for example like so
echo 'export PATH="/usr/local/sbin:$PATH"' >> ~/.bash_profile
$ brew config
HOMEBREW_VERSION: 1.7.5
ORIGIN: https://github.com/Homebrew/brew
HEAD: d639559c4de48faad79d3ecb1ec84dc851ea66f2
Last commit: 3 days ago
Core tap ORIGIN: https://github.com/Homebrew/homebrew-core
Core tap HEAD: bd29bc2b97641173dbe4e5ec2a6fe484dfa9dd93
Core tap last commit: 2 hours ago
HOMEBREW_PREFIX: /usr/local
HOMEBREW_GIT: git
CPU: octa-core 64-bit kabylake
Homebrew Ruby: 2.3.7 => /System/Library/Frameworks/Ruby.framework/Versions/2.3/usr/bin/ruby
Clang: 10.0 build 1000
Git: 2.19.0 => /usr/local/bin/git
Curl: 7.54.0 => /usr/bin/curl
Java: N/A
macOS: 10.13.6-x86_64
CLT: 9.4.0.0.1.1526532315
Xcode: 10.0
XQuartz: N/A