Patch #25901 by Tobias Oelgarte.
Bone transformations would be converted back and forth between different
representations when changing modes, which due to numerical errors could
lead to bone transformations slowly changing as you edit the armature.
Now the editmode head, tail and roll values are stored in bones and used
directly when entering edit mode. Head and tail were already there but
now we ensure they are the exact same value, roll was not yet there, so
we have a version patch for it.
The sub version was incremented to 1 for the version patch.
90cf78eb54