rhg: Accept different "invalid ignore pattern" error message formatting
At the moment rhg compiles all patterns into a single big regular expression,
so it’s not practical to find out which file the invalid bit of syntax
came from.
Differential Revision: https://phab.mercurial-scm.org/D11942
#require docutils gettext
$ $TESTDIR/check-gendoc pt_BR
checking for parse errors