Merge branch 'ds/completion-silence-in-tree-path-probe'

An internal ls-tree call made by completion code only to probe if
a path exists in the tree recorded in a commit object leaked error
messages when the path is not there.  It is not an error at all and
should not be shown to the end user.

* ds/completion-silence-in-tree-path-probe:
  git-completion.bash: silence "not a valid object" errors

contrib/completion/git-completion.bash

@@ -397,7 +397,7 @@ __git_complete_revlist_file ()
 		*)   pfx="$ref:$pfx" ;;
 		esac
 
-		__gitcomp_nl "$(git --git-dir="$(__gitdir)" ls-tree "$ls" \
+		__gitcomp_nl "$(git --git-dir="$(__gitdir)" ls-tree "$ls" 2>/dev/null \
 				| sed '/^100... blob /{
 				           s,^.*	,,
 				           s,$, ,