Would be nice to relax the "commit message rule"

[Sebastien Bacher]

The "lack of commit message" is an error that often bites people submitting changes, I would suggest to be a bit more tolerant and let the commit message to be "the message of the commit" when the merge has only 1 commit

Rational:

- if there is one commit, there is no real reason for the message of the merge to be different of the one of the one commit

- there are some people suggesting to use the description has commit, when the commit message is missing, that can be controversial: it's not uncommon to use the description to put review comments or details that are not interesting to the commit

- the most frequent case (especially for new contributors, who are the most likely to overlook the need for a commit message) is to have a trivial change with one commit, we can optimize for that case

[Sergio Schvezov (sergiusens)]

I am all in favor of the one commit means that's the commit message.