Replace manage_externals with git-fleximod in an error message

.lib/git-fleximod/git_fleximod/utils.py

@@ -241,7 +241,7 @@ def _hanging_msg(working_directory, command):
 has taken {hanging_sec} seconds. It may be hanging.
 
 The command will continue to run, but you may want to abort
-manage_externals with ^C and investigate. A possible cause of hangs is
+git-fleximod with ^C and investigate. A possible cause of hangs is
 when svn or git require authentication to access a private
 repository. On some systems, svn and git requests for authentication
 information will not be displayed to the user. In this case, the program