run-tests: fix broken regular expression
The regular expression in use passed tests because the test repo only
has single-digit changesets present. When I tried to use this for real
today, it broke, because the regular expression would only match a
single digit.
https://xkcd.com/1171/, or something like that.
#require docutils gettext
$ $TESTDIR/check-gendoc pt_BR
checking for parse errors