Script to downgrade WCs from 1.4 to 1.3

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  This is completely without warrantee or even any significant
  testing. It may trash your working copies !!!

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That said, here's a script I wrote when I found I had accidentally
upgraded lots of working copies which I didn't want to.

Max.

#!/usr/bin/python

import os, shutil, sys

class LE(RuntimeError):
  "Local Error exception class"
  pass

def downgrade_dir(dn):
  def fn(fn, dn=dn): return os.path.join(dn, '.svn', fn)
  # I'm aware that O_EXCL is broken on NFS, but Subversion uses it too,
  # so there is little point doing better than that.
  lockfd = os.open(fn('lock'), os.O_WRONLY | os.O_CREAT | os.O_EXCL)
  fl = open(fn('format'), 'r')
  fmt = fl.readline()
  fl.close()
  fmt = fmt.rstrip('\n')
  if fmt != '6':
    os.close(lockfd)
    os.unlink(fn('lock'))
    if fmt != '4':
      return "UNEXPECTED FORMAT: %s" % repr(fmt)
    else:
      return "is already format 4"
  # Because it is read-only
  os.unlink(fn('format'))
  fl = open(fn('format'), 'w')
  fl.write('downgrade-from-6-to-4-in-progress\n')
  fl.close()
  textbases = os.listdir(fn('text-base'))
  for textbase in textbases:
    if not textbase.endswith('.svn-base'):
      raise LE("Unexpected file %s in %s"
          % (repr(textbase), repr(fn('text-base'))))
    bn = textbase[:-9]
    propbase = fn(os.path.join('prop-base', bn+'.svn-base'))
    if not os.path.exists(propbase):
      fl = open(propbase, 'w')
      fl.close()
    propwork = fn(os.path.join('props', bn+'.svn-work'))
    if not os.path.exists(propwork):
      shutil.copyfile(propbase, propwork)
  propbase = fn('dir-prop-base')
  if not os.path.exists(propbase):
    fl = open(propbase, 'w')
    fl.close()
  propwork = fn('dir-props')
  if not os.path.exists(propwork):
    shutil.copyfile(propbase, propwork)
  fl = open(fn('format'), 'w')
  fl.write('4\n')
  fl.close()
  os.close(lockfd)
  os.unlink(fn('lock'))
  return "done"

def recurse_downgrade(dn):
  for dirpath, dirnames, filenames in os.walk(dn):
    if '.svn' in dirnames:
      sys.stderr.write("%s... " % repr(dirpath))
      sys.stderr.write(downgrade_dir(dirpath))
      sys.stderr.write('\n')
      dirnames.remove('.svn')

def main(args):
  for i in args:
    recurse_downgrade(i)

if __name__ == '__main__':
  main(sys.argv[1:])