Fix inverted conditionals in setup_develop

This fixes regressions introduced by:
    Change-Id: Ic97e68348f46245b271567893b447fcedbd7bd6e
    ("Handle non-zero exit code from git diff")

Change-Id: I053a292c287f3035eef37db2264eda06a170f9bc
Closes-Bug: 1287513
diff --git a/functions-common b/functions-common
index ed3d883..90cd3df 100644
--- a/functions-common
+++ b/functions-common
@@ -1248,7 +1248,7 @@
     # ``errexit`` requires us to trap the exit code when the repo is changed
     local update_requirements=$(cd $project_dir && git diff --exit-code >/dev/null || echo "changed")
 
-    if [[ $update_requirements = "changed" ]]; then
+    if [[ $update_requirements != "changed" ]]; then
         (cd $REQUIREMENTS_DIR; \
             $SUDO_CMD python update.py $project_dir)
     fi
@@ -1264,7 +1264,7 @@
     # a variable that tells us whether or not we should UNDO the requirements
     # changes (this will be set to False in the OpenStack ci gate)
     if [ $UNDO_REQUIREMENTS = "True" ]; then
-        if [[ $update_requirements = "changed" ]]; then
+        if [[ $update_requirements != "changed" ]]; then
             (cd $project_dir && git reset --hard)
         fi
     fi