Merge branch 'fix-invalid-syntax' into 'master'

Fix git syntax issue for git version older then 1.7.10

For #2067

See merge request !1599

app/models/repository.rb

@@ -238,7 +238,7 @@ class Repository
   end
 
   def last_commit_for_path(sha, path)
-    args = %W(git rev-list --max-count 1 #{sha} -- #{path})
+    args = %W(git rev-list --max-count=1 #{sha} -- #{path})
     sha = Gitlab::Popen.popen(args, path_to_repo).first.strip
     commit(sha)
   end