Fix .travis.yml

.travis.yml

@@ -98,7 +98,7 @@ script:
 
 after_script:
   - |
-    if [ $RUN_PYINSTALLER = "true" ]; then
+    if [ "$RUN_PYINSTALLER" = "true" ]; then
       # Cleanup
       pip uninstall -y $PIP_DEPENDENCIES