1   $ cat <<EOF >> $HGRCPATH

     2   > [extensions]

     3   > hooklib =

     4   > 

     5   > [phases]

     6   > publish = False

     7   > EOF

     8   $ hg init a

     9   $ hg --cwd a debugbuilddag '.:parent.*parent'

    10   $ hg --cwd a log -G

    11   o  changeset:   2:fa942426a6fd

    12   |  tag:         tip

    13   |  parent:      0:1ea73414a91b

    14   |  user:        debugbuilddag

    15   |  date:        Thu Jan 01 00:00:02 1970 +0000

    16   |  summary:     r2

    17   |

    18   | o  changeset:   1:66f7d451a68b

    19   |/   user:        debugbuilddag

    20   |    date:        Thu Jan 01 00:00:01 1970 +0000

    21   |    summary:     r1

    22   |

    23   o  changeset:   0:1ea73414a91b

    24      tag:         parent

    25      user:        debugbuilddag

    26      date:        Thu Jan 01 00:00:00 1970 +0000

    27      summary:     r0

    28   

    29   $ hg init b

    30   $ cat <<EOF >> b/.hg/hgrc

    31   > [hooks]

    32   > pretxnclose.reject_new_heads = \

    33   >   python:hgext.hooklib.reject_new_heads.hook

    34   > EOF

    35   $ hg --cwd b pull ../a

    36   pulling from ../a

    37   requesting all changes

    38   adding changesets

    39   adding manifests

    40   adding file changes

    41   error: pretxnclose.reject_new_heads hook failed: Changes on branch 'default' resulted in multiple heads

    42   transaction abort!

    43   rollback completed

    44   abort: Changes on branch 'default' resulted in multiple heads

    45   [255]

    46   $ hg --cwd b pull ../a -r 1ea73414a91b

    47   pulling from ../a

    48   adding changesets

    49   adding manifests

    50   adding file changes

    51   added 1 changesets with 0 changes to 0 files

    52   new changesets 1ea73414a91b (1 drafts)

    53   (run 'hg update' to get a working copy)