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
cat >> $HGRCPATH <<EOF
[extensions]
narrow=
[experimental]
changegroup3 = True
EOF