我正在尝试让自制桶回购工作。该存储库已在https://github.com/skysquirrel/homebrew-cask设置，公式位于Casks/qgis-ltr-simple.rb.
在这一点上，它似乎brew install skysquirrel/cask/qgis-ltr-simple应该工作，但它没有：
$ brew install SkySquirrel/cask/qgis-ltr-simple
==> Tapping skysquirrel/cask
Cloning into '/usr/local/Homebrew/Library/Taps/skysquirrel/homebrew-cask'...
remote: Enumerating objects: 4, done.
remote: Counting objects: 100% (4/4), done.
remote: Compressing objects: 100% (2/2), done.
remote: Total 4 (delta 0), reused 4 (delta 0), pack-reused 0
Unpacking objects: 100% (4/4), done.
Tapped 1 cask (28 files, 24KB).
Error: No available formula with the name "skysquirrel/cask/qgis-ltr-simple"
但是它确实出现brew cask info：
$ brew cask info skysquirrel/cask/qgis-ltr-simple
==> Tapping skysquirrel/cask
Cloning into '/usr/local/Homebrew/Library/Taps/skysquirrel/homebrew-cask'...
remote: Enumerating objects: 4, done.
remote: Counting objects: 100% (4/4), done.
remote: Compressing objects: 100% (2/2), done.
remote: Total 4 (delta 0), reused 4 (delta 0), pack-reused 0
Unpacking objects: 100% (4/4), done.
Tapped 1 cask (28 files, 24KB).
qgis-ltr-simple: 2.18.24-1
https://qgis.org/
Not installed
...
它确实出现在brew search：
$ brew search qgis-ltr-simple
==> Casks
qgis-ltr-simple
看来我可以这样做：
brew tap skysquirrel/cask
brew install qgis-ltr-simple
但我想找出为什么一个班轮不工作。