repair: move check for existing transaction earlier
Several benefits:
* Gets close the comment describing it
* Splits off unrelated comment about "backup" argument
* Error checking is customarily done early
* If we added an early return to the method, it would still
consistently fail if there was an existing transaction (so
we would find and fix that case quickly)
One test needs updating with for this change, because we no longer
create the backup bundle before we fail. I don't see much reason to
create that backup bundle. If some command was adding content and then
trying to strip it as well within the transaction, we would have a
backup for the user, but the risk of that not being discovered in
development seems very small.
#require bzr
$ . "$TESTDIR/bzr-definitions"
$ cat > ghostcreator.py <<EOF
> import sys
> from bzrlib import workingtree
> wt = workingtree.WorkingTree.open('.')
>
> message, ghostrev = sys.argv[1:]
> wt.set_parent_ids(wt.get_parent_ids() + [ghostrev])
> wt.commit(message)
> EOF
ghost revisions
$ mkdir test-ghost-revisions
$ cd test-ghost-revisions
$ bzr init -q source
$ cd source
$ echo content > somefile
$ bzr add -q somefile
$ bzr commit -q -m 'Initial layout setup'
$ echo morecontent >> somefile
$ python ../../ghostcreator.py 'Commit with ghost revision' ghostrev
$ cd ..
$ hg convert source source-hg
initializing destination source-hg repository
scanning source...
sorting...
converting...
1 Initial layout setup
0 Commit with ghost revision
$ glog -R source-hg
o 1@source "Commit with ghost revision" files: somefile
|
o 0@source "Initial layout setup" files: somefile
$ cd ..