Keystone Identity Service on OpenStack: Database url issue

I remember one time trying to debug a problem with the setup of keystone.

It took me FOREVER to figure it out.

It was when I was, as part of set up procedure, running the script:
su -s /bin/sh -c "keystone-manage db_sync" keystone

This script will exit silently with a "1" code if it does not run. You MUST check the $? in bash to make sure the damned thing ran.

When I saw the "1" code, I went and checked the keystone log, which said:

2017-12-31 23:28:21.807 13029 CRITICAL keystone [-] NoSuchModuleError: Can't load plugin: sqlalchemy.dialects:mysql.pymsql
2017-12-31 23:28:21.807 13029 ERROR keystone Traceback (most recent call last):
2017-12-31 23:28:21.807 13029 ERROR keystone   File "/bin/keystone-manage", line 10, in <module>
2017-12-31 23:28:21.807 13029 ERROR keystone     sys.exit(main())
2017-12-31 23:28:21.807 13029 ERROR keystone   File "/usr/lib/python2.7/site-packages/keystone/cmd/manage.py", line 44, in main
2017-12-31 23:28:21.807 13029 ERROR keystone     cli.main(argv=sys.argv, config_files=config_files)
2017-12-31 23:28:21.807 13029 ERROR keystone   File "/usr/lib/python2.7/site-packages/keystone/cmd/cli.py", line 1312, in main
...

I started looking at all of these packages I'd installed, checking them (they were all there). I then went in search of help on google. And yes, the message was there, but no help fixing it.

I then realized...the URL was wrong in the file. Problem is, the naked eye can't seem to spot this error:

Incorrect URL:
connection = mysql+pymsql://keystone:KEYSTONE_DBPASS@controller/keystone

Correct URL:
connection = mysql+pymysql://keystone:KEYSTONE_DBPASS@controller/keystone

Optically, very hard to see that missing second "y" in "mysql" because of the "py". Fortunately, I lost only 30 minutes on this issue this time. Earlier, when installing Newton, I lost an entire day or more.