largefile: use sysstr to check for attribute presence in `rebase` wrapping

We do not need bytes here.

hgext/largefiles/overrides.py

@@ -1167,7 +1167,7 b' def hgclone(orig, ui, opts, *args, **kwa'
 
 @eh.wrapcommand(b'rebase', extension=b'rebase')
 def overriderebasecmd(orig, ui, repo, **opts):
-    if not util.safehasattr(repo, b'_largefilesenabled'):
+    if not util.safehasattr(repo, '_largefilesenabled'):
         return orig(ui, repo, **opts)
 
     resuming = opts.get('continue')