tests: fix test-chg.t to work with py3 (no setprocname)

Differential Revision: https://phab.mercurial-scm.org/D7551

tests/test-chg.t

@@ -229,11 +229,13 b' check that server events are recorded:'
   server.log.1
 
 print only the last 10 lines, since we aren't sure how many records are
-preserved:
+preserved (since setprocname isn't available on py3, the 10th-most-recent line
+is different when using py3):
 
   $ cat log/server.log.1 log/server.log | tail -10 | filterlog
+  YYYY/MM/DD HH:MM:SS (PID)> confighash = ... mtimehash = ... (py3 !)
   YYYY/MM/DD HH:MM:SS (PID)> forked worker process (pid=...)
-  YYYY/MM/DD HH:MM:SS (PID)> setprocname: ...
+  YYYY/MM/DD HH:MM:SS (PID)> setprocname: ... (no-py3 !)
   YYYY/MM/DD HH:MM:SS (PID)> received fds: ...
   YYYY/MM/DD HH:MM:SS (PID)> chdir to '$TESTTMP/extreload'
   YYYY/MM/DD HH:MM:SS (PID)> setumask 18