Pre-update hook to remove subrepositories for branch switching to work.

switch_branch_with_subrepo.py

'''Removes .hgsub and any subrepos when switching branches in the parent repository

To activate this hook, add this to your ~/.hgrc file:

[extensions]
switch_branch_with_subrepo =

[hooks]
preupdate.switch_branch_with_subrepo = python:switch_branch_with_subrepo.preupdate
'''

from mercurial.node import short
from mercurial import util
import os
import shutil

def preupdate(ui, repo, hooktype, parent1, parent2):
   """
   Remove subrepositories and .hgsub file before updating to a revision that spans branches
   """
   if parent2 == None or parent2 == '':
      # If the second parent is set, this is a merge, so don't remove files!!
      # http://hgbook.red-bean.com/read/handling-repository-events-with-hooks.html#sec:hook:preupdate
      return False
      #pass

   # repo[None] is the change context of the working copy and could be dirty, so has no revision.
   # Retrieve the parent to refer to the last commited revision.
   sourceRevision = repo[None].parents()[0]
   sourceBranch = sourceRevision.branch()
   ui.write("Current revision %s on branch %s" % (sourceRevision, sourceBranch))
   ui.write('\n')

   targetRevision = repo[parent1]
   targetBranch = targetRevision.branch()
   ui.write("Switching to %s on branch %s" % (targetRevision, targetBranch))
   ui.write('\n')

   ui.write(repo.root)
   ui.write('\n')

   hgsub = os.path.join(repo.root, '.hgsub')
   if os.path.exists(hgsub):
      ui.write('Source branch has subrepositories\n')
      hgsubfile = open(hgsub, 'r')
      for subrepo in hgsubfile:
         parts = subrepo.split('=')
         shutil.rmtree(os.path.join(repo.root,parts[0].strip()))
      hgsubfile.close()
      os.remove(hgsub)
   else:
      ui.write('Source branch has no subrepositories\n')
   return True