tests/test-dirstate-nonnormalset.t

rebase: fail-fast the pull if working dir is not clean (BC)

Refuse to run 'hg pull --rebase' if there are uncommitted changes:
so that instead of going ahead with fetching changes and then suddenly aborting
the rebase, we can warn user of uncommitted changes (or unclean repo state)
right up front.
In tests, we create a 'histedit' session to verify that also an unfinished
state is detected and handled.

  $ cat >> $HGRCPATH << EOF
  > [ui]
  > logtemplate="{rev}:{node|short} ({phase}) [{tags} {bookmarks}] {desc|firstline}\n"
  > [extensions]
  > dirstateparanoidcheck = $TESTDIR/../contrib/dirstatenonnormalcheck.py
  > [experimental]
  > nonnormalparanoidcheck = True
  > [devel]
  > all-warnings=True
  > EOF
  $ mkcommit() {
  >    echo "$1" > "$1"
  >    hg add "$1"
  >    hg ci -m "add $1"
  > }

  $ hg init testrepo
  $ cd testrepo
  $ mkcommit a
  $ mkcommit b
  $ mkcommit c
  $ hg status