brew-bundle: add path support.

Closes Homebrew/homebrew#24384.

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

Library/Contributions/cmd/brew-bundle.rb

@@ -1,17 +1,33 @@
 # brew-bundle.rb
-# Looks for a "Brewfile" in the current directory and runs each line
+#
-# as a brew command.
+# Usage: brew bundle [path]
+#
+# Looks for a Brewfile and runs each line as a brew command.
+#
+# brew bundle              # Looks for "./brewfile"
+# brew bundle path/to/dir  # Looks for "./path/to/dir/brewfile"
+# brew bundle path/to/file # Looks for "./path/to/file"
 #
 # For example, given a Brewfile with the following contents:
+#
 # tap foo/bar
 # install spark
 #
 # Running `brew bundle` will run the commands `brew tap foo/bar`
 # and `brew install spark`.
 
-raise 'Cannot find Brewfile' unless File.exist? 'Brewfile'
+if ARGV.empty? then
+	path = 'brewfile'
+else
+	path = ARGV[0]
+	if File.directory? path then
+		path = path + '/brewfile'
+	end
+end
 
-File.readlines('Brewfile').each do |line|
+raise "No such Brewfile: #{path}" unless File.exist? path
+
+File.readlines(path).each do |line|
   command = line.chomp
   next if command.empty?
   next if command.chars.first == '#'