nodemap: fix missing r-prefix on regular expression
Looking at this regular expression, it's pretty obvious from reading
it that it wanted to match literal ., but since the r was missing on
the pattern it was matching any character. I guess we're just lucky
nothing bad happened as a result. This was automatically fixed by
pyupgrade, but I split it out into its own change because it seemed
important.
Differential Revision: https://phab.mercurial-scm.org/D8254
#require docutils gettext
$ $TESTDIR/check-gendoc sv
checking for parse errors