I've run
$ python manage.py db history
And as a result I got
vagrant@precise64:/vagrant$ python manage.py db history
Rev: 29c319804087 (head)
Parent: 313837798149
Path: migrations/versions/29c319804087_.py
empty message
Revision ID: 29c319804087
Revises: 313837798149
Create Date: 2014-03-05 21:26:32.538027
Rev: 313837798149
Parent: 280061454d2a
Path: migrations/versions/313837798149_.py
empty message
Revision ID: 313837798149
Revises: 280061454d2a
Create Date: 2014-01-10 03:19:39.838932
Rev: 280061454d2a
Parent: None
Path: migrations/versions/280061454d2a_.py
empty message
Revision ID: 280061454d2a
Revises: None
Create Date: 2013-12-08 03:04:55.885033
Rev: 2e74f61d3b80 (head)
Parent: 49501407aec9
Path: migrations/versions/2e74f61d3b80_o2_lease.py
o2 lease
Revision ID: 2e74f61d3b80
Revises: 49501407aec9
Create Date: 2014-02-28 10:38:06.187420
Rev: 49501407aec9
Parent: None
Path: migrations/versions/49501407aec9_.py
empty message
Revision ID: 49501407aec9
Revises: None
Create Date: 2014-01-22 11:27:08.002187
What you can see here is 2 different branches. One starts from 49501407aec9 and second from 280061454d2a. I moved 49501407aec9 and the following 2e74f61d3b80 out of the /versions directory, run
$ python manage.py db revision
and it created a new migration file.