safehasattr: pass attribute name as string instead of bytes

This is a step toward replacing `util.safehasattr` usage with plain `hasattr`.
The builtin function behave poorly in Python2 but this was fixed in Python3.

These change are done one by one as they tend to have a small odd to trigger
puzzling breackage.

mercurial/sslutil.py

@@ -419,7 +419,7 b' def wrapsocket(sock, keyfile, certfile, '
             pass
 
         # Try to print more helpful error messages for known failures.
-        if util.safehasattr(e, b'reason'):
+        if util.safehasattr(e, 'reason'):
             # This error occurs when the client and server don't share a
             # common/supported SSL/TLS protocol. We've disabled SSLv2 and SSLv3
             # outright. Hopefully the reason for this error is that we require