Cannot migrate with newest master version of the Tracker

[TreZc0]

Hey everyone,
the toplevel here references a really old (2 years) version of the tracker. Sadly, we kinda need to use the current master version with its bugfixes.
The deployment goes alright up until i try to do python manage.py migrate:
Applying tracker.0001_squashed_0039_upgrade_to_19...Traceback (most recent call last):

  File "manage.py", line 13, in <module>
    execute_from_command_line(sys.argv)
  File "/usr/local/lib/python2.7/dist-packages/django/core/management/__init__.py", line 353, in execute_from_command_line
    utility.execute()
  File "/usr/local/lib/python2.7/dist-packages/django/core/management/__init__.py", line 345, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/usr/local/lib/python2.7/dist-packages/django/core/management/base.py", line 348, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/usr/local/lib/python2.7/dist-packages/django/core/management/base.py", line 399, in execute
    output = self.handle(*args, **options)
  File "/usr/local/lib/python2.7/dist-packages/django/core/management/commands/migrate.py", line 200, in handle
    executor.migrate(targets, plan, fake=fake, fake_initial=fake_initial)
  File "/usr/local/lib/python2.7/dist-packages/django/db/migrations/executor.py", line 92, in migrate
    self._migrate_all_forwards(plan, full_plan, fake=fake, fake_initial=fake_initial)
  File "/usr/local/lib/python2.7/dist-packages/django/db/migrations/executor.py", line 121, in _migrate_all_forwards
    state = self.apply_migration(state, migration, fake=fake, fake_initial=fake_initial)
  File "/usr/local/lib/python2.7/dist-packages/django/db/migrations/executor.py", line 198, in apply_migration
    state = migration.apply(state, schema_editor)
  File "/usr/local/lib/python2.7/dist-packages/django/db/migrations/migration.py", line 115, in apply
    operation.state_forwards(self.app_label, project_state)
  File "/usr/local/lib/python2.7/dist-packages/django/db/migrations/operations/fields.py", line 181, in state_forwards
    state.models[app_label, self.model_name_lower].fields
KeyError: ('tracker', u'credentialsmodel')

I already cleaned all required dist-packages and reinstalled them hoping this would fix the issue, but sadly it won't - any ideas?

[jofo8948]

Try removing the squashed migration from the tracker migrations folder. That helped for me.
The squashed ones are just a compact way of applying all the others in one go to save time.

Except when it doesn't work.
But you might want to stick with a version before the 1.9 upgrade. Been having various issues with it that I had to patch myself for now.