Fix wrong check for empty files

The condition needs to be negated, we want to remove files
where the grep for non-empty lines does not succeed.

Change-Id: I0111bedcd3bb4affde8b9bd7cd2a21e6849c1513

jenkins/scripts/common_translation_update.sh

@@ -290,7 +290,7 @@ function filter_commits ()
     for f in `git diff --cached --name-only --diff-filter=A`
     do
         # Files should have at least one non-empty msgid string.
-        if grep -q 'msgid "[^"]' "$f" ; then
+        if ! grep -q 'msgid "[^"]' "$f" ; then
             git reset -q "$f"
             rm "$f"
         fi