a-1.0:
start version

a-1.1:
can be upgraded to from a-1.0. Module a has changed

a-1.2:
can be upgraded to from a-1.1.
No module have changed, but priv dir is added including one 'file'

a-9.0:
can be upgrade to from a-1.0
Changes a_sup correctly - to test successful upgrade of supervisor

a-9.1:
can be upgrade to from a-1.0
Changes a_sup faulty - to test failing upgrade of supervisor

b-1.0:
start version, includes b_lib and b_server

b-2.0:
can be upgraded to from b-1.0.
Removes b_lib (brutal_purge) and updates b_server (soft_purge)
* The diff in purge method is important for test "check_and_purge", in
  order to check that the purge option to check_install_release works
  for both methods.

many_mods-1.0:
start version.
m:start/1 starts N procs, each calling Mod:bar() in all other modules (m1-m10).
m1-m10: implements bar() which returns a big constant.
The point is to get many processes with references to many modules,
and then load the modules again so that old code exists. See tests
otp_9395_update_many_mods and otp_9395_rm_many_mods.

many_mods-1.1:
can be upgraded to from many_mods-1.0. Updates modules m1-m10.

many_mods-2.0:
can be upgraded to from many_mods-1.0. Removes modules m1-m10.