Update brew tap to work without 'homebrew-'

Currently `brew tap` only works on repos with 'homebrew-' in their name.

This version tries the repo name as is and then falls back to try
'homebrew-repo' only if that fails.

I've also tweaked the regex  in tap_args to allow '-' in repo names. The
previous regex required a match on \w. This made it impossible for people
to tap repos with names like 'username/why-not'.

Closes #18366.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>

Library/Homebrew/cmd/tap.rb

@@ -24,7 +24,21 @@ def install_tap user, repo
     # we downcase to avoid case-insensitive filesystem issues
     tapd = HOMEBREW_LIBRARY/"Taps/#{user.downcase}-#{repo.downcase}"
     raise "Already tapped!" if tapd.directory?
-    abort unless system "git clone https://github.com/#{repouser}/homebrew-#{repo} #{tapd}"
+    # First try tapping the repo name as is. If that fails, fall back to
+    # 'homebrew-repo'.
+    stdout = `git clone https://github.com/#{repouser}/#{repo} #{tapd} 2>/dev/null`
+    unless $?.success?
+      stdout = `git clone https://github.com/#{repouser}/homebrew-#{repo} #{tapd} 2>&1`
+      if $?.success?
+        repo = "homebrew-" + repo
+      else
+        abort <<-EOS.undent
+          Neither #{repouser}/#{repo} nor #{repouser}/homebrew-#{repo} tapped.
+          Please check the tap name and try again.
+        EOS
+      end
+    end
+    puts stdout
 
     files = []
     tapd.find_formula{ |file| files << tapd.basename.join(file) }
@@ -34,7 +48,7 @@ def install_tap user, repo
     # Figure out if this repo is private
     # curl will throw an exception if the repo is private (Github returns a 404)
     begin
-      curl('-Ifso', '/dev/null', "https://api.github.com/repos/#{repouser}/homebrew-#{repo}")
+      curl('-Ifso', '/dev/null', "https://api.github.com/repos/#{repouser}/#{repo}")
     rescue
       puts
       puts "It looks like you tapped a private repository"
@@ -43,7 +57,7 @@ def install_tap user, repo
       puts "following command:"
       puts
       puts "   cd #{tapd}"
-      puts "   git remote set-url origin git@github.com:#{repouser}/homebrew-#{repo}.git"
+      puts "   git remote set-url origin git@github.com:#{repouser}/#{repo}.git"
       puts
     end
   end
@@ -102,7 +116,7 @@ def repair_taps
   private
 
   def tap_args
-    ARGV.first =~ %r{^(\S+)/(homebrew-)?(\w+)$}
+    ARGV.first =~ %r{^(\S+)/(homebrew-)?([-\w]+)$}
     raise "Invalid usage" unless $1 and $3
     [$1, $3]
   end