Merge branch 'jk/no-clobber-dangling-symref-with-fetch'

"git fetch" can clobber a symref that is dangling when the remote-tracking HEAD is set to auto update, which has been corrected. * jk/no-clobber-dangling-symref-with-fetch: refs: do not clobber dangling symrefs t5510: prefer "git -C" to subshell for followRemoteHEAD tests t5510: stop changing top-level working directory t5510: make confusing config cleanup more explicit