Also check for sys._MEIPASS before assuming PyInstallerness (#526)

Fixes #525

Author: akx

babel/localedata.py

@@ -22,7 +22,7 @@
 
 
 def get_base_dir():
-    if getattr(sys, 'frozen', False):
+    if getattr(sys, 'frozen', False) and getattr(sys, '_MEIPASS', None):
         # we are running in a |PyInstaller| bundle
         basedir = sys._MEIPASS
     else: