[Python-Dev] Bizarre mtime behaviour

[Antoine Pitrou]

Hello,

I wondered if someone had a clue about the following behaviour.
While debugging an erratic test_mailbox failure on RDM's buildbot (and other
machines), it turned out that the system sometimes set the wrong mtime on a
directory:

$ date && python -c 'import os; os.link("setup.py", "t/c")' && stat t && date

Sun Nov  1 09:49:04 EST 2009
  File: `t'
  Size: 144             Blocks: 0          IO Block: 4096   directory
Device: 811h/2065d      Inode: 223152      Links: 2
Access: (0755/drwxr-xr-x)  Uid: ( 1001/  pitrou)   Gid: ( 1005/  pitrou)
Access: 2009-11-01 09:10:11.000000000 -0500
Modify: 2009-11-01 09:49:03.000000000 -0500
Change: 2009-11-01 09:49:03.000000000 -0500
Sun Nov  1 09:49:04 EST 2009

As you see above, the mtime for directory 't' is set to a full second before the
actual modification has happened.

Sprinkling traces of time.time() and os.path.getmtime() on Lib/mailbox.py shows
this is exactly what trips up test_mailbox. I've got posted a patch to fix it
(see issue #6896), but I would like to know if such OS behaviour is normal.

Regards

Antoine.