According to the man pages on Gentoo Linux and Tru64, EACCES or EAGAIN

can be returned if fcntl (lockf) fails.  This fixes the test failure
on Tru64 by checking for either error rather than just EAGAIN.

Lib/mailbox.py

@@ -1805,7 +1805,7 @@ def _lock_file(f, dotlock=True):
             try:
                 fcntl.lockf(f, fcntl.LOCK_EX | fcntl.LOCK_NB)
             except IOError, e:
-                if e.errno == errno.EAGAIN:
+                if e.errno in (errno.EAGAIN, errno.EACCES):
                     raise ExternalClashError('lockf: lock unavailable: %s' %
                                              f.name)
                 else: