tests/test-extra-filelog-entry.t

dirstate: rename forget to drop

It has substantially different semantics from forget at the command
layer, so change it to avoid confusion.

We can't simply combine it with remove because we need to explicitly
drop non-added files in some cases like commit.

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    offset  length   base linkrev nodeid       p1           p2
       0         0       3      0       0 1e88685f5dde 000000000000 000000000000