templater: abstract ifcontains() over wrapped types
This allows us to make .keytype private.
There's a minor BC that a hybrid dict/list of keytype=None now strictly
checks the type of the needle. For example, {ifcontains(rev, files)} no longer
matches a file named "1" at the rev=1. I made this change for consistency
with the get(dict, key) function. We can restore the old behavior by making
keytype=bytes the default if desired.
Issue351: mq: qrefresh can create extra revlog entry
$ echo "[extensions]" >> $HGRCPATH
$ echo "mq=" >> $HGRCPATH
$ hg init
$ hg qinit
$ echo b > b
$ hg ci -A -m foo
adding b
$ echo cc > b
$ hg qnew -f foo.diff
$ echo b > b
$ hg qrefresh
$ hg debugindex b
rev linkrev nodeid p1 p2
0 0 1e88685f5dde 000000000000 000000000000