git-prompt: fix uninitialized variable

First use is in the form:  local var; ...; var=$var$whatever...

If the variable was unset (as bash and others do after "local x"),
then it would error if set -u is in effect.

Also, many shells inherit the existing value after "local var"
without init, but in this case it's unlikely to have a prior value.

Now we initialize it.

(local var= is enough, but local var="" is the custom in this file)

Signed-off-by: Avi Halachmi (:avih) <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: avih

contrib/completion/git-prompt.sh

@@ -116,7 +116,7 @@ printf -v __git_printf_supports_v -- '%s' yes >/dev/null 2>&1
 __git_ps1_show_upstream ()
 {
 	local key value
-	local svn_remote svn_url_pattern count n
+	local svn_remote svn_url_pattern="" count n
 	local upstream_type=git legacy="" verbose="" name=""
 
 	svn_remote=()