$ cat <<EOF >> $HGRCPATH
> [extensions]
> hooklib =
>
> [phases]
> publish = False
> EOF
$ hg init a
$ hg --cwd a debugbuilddag .
$ hg --cwd a phase --public 0
$ hg init b
$ cat <<EOF >> b/.hg/hgrc
> [hooks]
> pretxnclose-phase.enforce_draft_commits = \
> python:hgext.hooklib.enforce_draft_commits.hook
> EOF
$ hg --cwd b pull ../a
pulling from ../a
requesting all changes
adding changesets
adding manifests
adding file changes
error: pretxnclose-phase.enforce_draft_commits hook failed: New changeset 1ea73414a91b in phase 'public' rejected
transaction abort!
rollback completed
abort: New changeset 1ea73414a91b in phase 'public' rejected
[255]
$ hg --cwd a phase --force --draft 0
$ hg --cwd b pull ../a
pulling from ../a
requesting all changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 0 changes to 0 files
new changesets 1ea73414a91b (1 drafts)
(run 'hg update' to get a working copy)
$ hg --cwd a phase --public 0
$ hg --cwd b pull ../a
pulling from ../a
searching for changes
no changes found
error: pretxnclose-phase.enforce_draft_commits hook failed: Phase change from 'draft' to 'public' for 1ea73414a91b rejected
abort: Phase change from 'draft' to 'public' for 1ea73414a91b rejected
[255]