log messages after they've been entered. This is more flexible than
using the editinfo script since it works for all log message types
and doesn't have to deal with trying to run the editor for the user.
The problem is that the verifymsg script can't modify the file like
editinfo can, which makes it useless for cleaning up the message (as is
needed for remote commits etc). This change causes the verifymsg handler
to read back the message after the verify script has run and returned an
"OK" exit code.