This commit break line continuation prompts for unbalanced parentheses in the psql binary. Skimming through this thread, I don't see that this is intentional or has been noticed before.
with psql -X
Before:
jjanes=# asdf ( jjanes(#
Now:
jjanes=# asdf ( jjanes-#
I've looked through the parts of the commit that change psql, but didn't see an obvious culprit.