Git describe finding wrong tag

I just encountered an odd situation where `git describe` insists on finding the wrong tag. In my case, I tagged a branch, then merged it into another branch, and now `git describe` in that other branch decides that it should emit a tag name that's over 200 commits old rather than the one that's a single commit away.

% git --version git version 1.7.4.31.g3f8c4 % git describe build_1.2.2_applestore_1-203-g742967b % git describe HEAD^2 build_1.2.2

Is there any rational for why git-describe is opting for the much older commit?

-Kevin Ballard