scm: git: use scm_cmd() in adapter tags().

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@5046 e93f8b46-1217-0410-a6f0-8f06a7374b81

lib/redmine/scm/adapters/git_adapter.rb

@@ -92,10 +92,12 @@ module Redmine
 
         def tags
           return @tags if @tags
-          cmd = "#{self.class.sq_bin} --git-dir #{target('')} tag"
-          shellout(cmd) do |io|
+          cmd_args = %w|tag|
+          scm_cmd(*cmd_args) do |io|
             @tags = io.readlines.sort!.map{|t| t.strip}
           end
+        rescue ScmCommandAborted
+          nil
         end
 
         def default_branch