debugbuilddag: take wlock to cover '.hg/localtags'

This debug command can write local tags. local tags are in the .hg directory and
should be covered by the 'wlock'. This is now covered.

mercurial/commands.py

@@ -1987,8 +1987,9 b' def debugbuilddag(ui, repo, text=None,'
 
     tags = []
 
-    lock = tr = None
+    wlock = lock = tr = None
     try:
+        wlock = repo.wlock()
         lock = repo.lock()
         tr = repo.transaction("builddag")
 
@@ -2073,7 +2074,7 b' def debugbuilddag(ui, repo, text=None,'
             repo.vfs.write("localtags", "".join(tags))
     finally:
         ui.progress(_('building'), None)
-        release(tr, lock)
+        release(tr, lock, wlock)
 
 @command('debugbundle',
         [('a', 'all', None, _('show all details')),