largefile: use sysstr to check for attribute presence in `getstatuswriter`

We do not need bytes here.

hgext/largefiles/lfutil.py

@@ -814,7 +814,7 b' def getstatuswriter(ui, repo, forcibly=N'
     Otherwise, this returns the function to always write out (or
     ignore if ``not forcibly``) status.
     """
-    if forcibly is None and util.safehasattr(repo, b'_largefilesenabled'):
+    if forcibly is None and util.safehasattr(repo, '_largefilesenabled'):
         return repo._lfstatuswriters[-1]
     else:
         if forcibly: