Earlier quoted context omitted.
Bad commits are the absolute most difficult thing to reverse when they get released and the userbase codes to them. When I don't pay super close attention to what's being contributed, it creates three times as much work after I let it through.
How often is commit bad enough to require revert, yet made it through testing and got released?
Examples of PRs that "work" exactly as intended yet are the wrong way to solve the problem:
https://github.com/zzzeek/sqlalchemy/pull/381
https://github.com/zzzeek/sqlalchemy/pull/382
Here's a large PR:
https://github.com/zzzeek/sqlalchemy/pull/365
that after lots and lots of back and forth I finally merged with lots of edits from me at: https://github.com/zzzeek/sqlalchemy/commit/7d3da6f850dca54b...
...aannnnndddd - after all that work and testing, it was wrong! Fortunately someone caught the mistake within the beta release:
https://bitbucket.org/zzzeek/sqlalchemy/issues/4072/mysqldml...
if I had released that fully and the whole world coded to "mysql.insert.values.bar == 5", that's broken API since it breaks the values() method. Backwards-incompatible fix required.