repopick: fix broken pipe error from "repo list"

  * the subprocess running "repo list" was not closed cleanly
    if the branch was found

Change-Id: Ie659966f3a670b25ab076a8dc723c4235760d04e
Merge branch 'cm-10.2' of git://github.com/CyanogenMod/android_build into cm-10.2-ace