Revert "Add mq patch to branch output"

This reverts commit 8023f6f5dc.

fixes #1035

autoload/airline/extensions/branch.vim

@@ -102,11 +102,6 @@ endfunction
 
 function! s:get_hg_branch()
   if s:has_lawrencium
-    let mq=system('hg qtop')
-    if v:shell_error==0
-      let mq=matchstr(mq, '.*\ze\n')
-      return lawrencium#statusline(). '/'. mq
-    endif
     return lawrencium#statusline()
   endif
   return ''