tests/test-mq-qimport-fail-cleanup.t

rebase: allow aborting if last-message.txt is missing

Previously, if .hg/rebasestate existed but .hg/last-message.txt was missing, 'hg
rebase --abort' would say there's no rebase in progress but 'hg checkout foo'
would say 'abort: rebase in progress'. It turns out loading the collapse message
will throw a "no rebase in progress" error if the file doesn't exist, even
though .hg/rebasestate obviously indicates a rebase is in progress.

The fix is to only throw an exception if we're trying to --continue, and to just
eat the issues if we're doing --abort.

This issue is exposed by us writing the rebase state earlier in the process.
This will be used by later patches to ensure the user can appropriately 'hg
rebase --abort' if there's a crash before the first the first commit has
finished rebasing. Tests cover all of this. The only negative affect is we now
require a hg rebase --abort in a very specific exception case, as shown in the
test.

Failed qimport of patches from files should cleanup by recording successfully
imported patches in series file.

  $ echo "[extensions]" >> $HGRCPATH
  $ echo "mq=" >> $HGRCPATH
  $ hg init repo
  $ cd repo
  $ echo a > a
  $ hg ci -Am'add a'
  adding a
  $ cat >b.patch<<EOF
  > diff --git a/a b/a
  > --- a/a
  > +++ b/a
  > @@ -1,1 +1,2 @@
  >  a
  > +b
  > EOF

empty series

  $ hg qseries

qimport valid patch followed by invalid patch

  $ hg qimport b.patch fakepatch
  adding b.patch to series file
  abort: unable to read file fakepatch
  [255]

valid patches before fail added to series

  $ hg qseries
  b.patch

  $ hg pull -q -r 0 . # update phase
  $ hg qimport -r 0
  abort: revision 0 is not mutable
  (see 'hg help phases' for details)
  [255]

  $ cd ..