% appears twice in actionbar text

Verification builds: 1.5.0.14_RC (1001349 - Release)

Summary: When a name-tagged entity contains the % symbol, a double %% is output when querying it via an actionbar title.

Impact: A double % appears.

Repro Steps:

1. Create an armor stand and name-tag it as `10%`
2. Create a repeating command block with `/testfor @e[type=armor_stand]`

Observed Results: The action bar says `10%%`

Expected Results: The action bar should say `10%`

Screenshots/Videos attached: See attachment.