Strong disagree. Commit messages that are only one sentence long should be reserved for truly trivial things. Signed, someone who regularly comes back to 18+ year old commits and enjoys the valuable details that would have been lost.
In my experience and that of most of my friends both French and German, that is wrong. The French rail system may have its flaws (it does), but the German one is so much worse
While I agree that people should have moved on for a while, the idea that porting Python 2 to 3 only involves "find and replace" or a tool like 2to3 is only true in the most trivial cases. Anything that touches bytes, unicode, network or files to do anything remotely involved needs a lot more care. I should know, our codebase still suffers from the occasional bug due to this, even though it's been years.