The source revision variable implemented in the scope of
MDEV-12583 was a useful addition. It would have been much more useful if it was also reflected in the error log. I don't think that's where we should be concerned about one extra line per server runtime session.
I've set the version to 10.3 because I don't think this kind of change breaks any post-GA rules, but please feel free to change it to 10.4 if it does.
It could also be useful if handle_fatal_signal() displayed the source code revision.