[BUG] git fetch --prune --tags origin deletes all remote branches origin/*

Running the simple command `git fetch --prune --tags origin` will delete every single remote branch refs/remotes/origin/*, with the sole exception of refs/remotes/origin/HEAD. This is wildly unexpected behavior. This was reproduced on the tip of the next branch, with version git version 1.7.2.2.440.g49ea7.

git fetch --prune --tags origin

 x [deleted]         (none)     -> origin/ahaney/login_problem_debug
 x [deleted]         (none)     -> origin/ahaney/tocfixes
 x [deleted]         (none)     -> origin/develop
   (refs/remotes/origin/HEAD has become dangling)
 x [deleted]         (none)     -> origin/jon/contentupdates
 x [deleted]         (none)     -> origin/jon/ingest_safety
 x [deleted]         (none)     -> origin/jon/overview
 x [deleted]         (none)     -> origin/master
 x [deleted]         (none)     -> origin/v1_rejection/plan_a

git fetch origin

From [redacted]
 * [new branch]      ahaney/login_problem_debug -> origin/ahaney/login_problem_debug
 * [new branch]      ahaney/tocfixes -> origin/ahaney/tocfixes
 * [new branch]      develop    -> origin/develop
 * [new branch]      jon/contentupdates -> origin/jon/contentupdates
 * [new branch]      jon/ingest_safety -> origin/jon/ingest_safety
 * [new branch]      jon/overview -> origin/jon/overview
 * [new branch]      master     -> origin/master
 * [new branch]      v1_rejection/plan_a -> origin/v1_rejection/plan_a

-Kevin Ballard