tests/test-dispatch.py.out

util: add utility function to skip avoiding file stat ambiguity if EPERM

Now, advancing stat.st_mtime by os.utime() is used to avoid file stat
ambiguity. But according to POSIX specification, utime(2) with an
explicit time information is permitted only for a process with:

  - the effective user ID equal to the user ID of the file, or
  - appropriate privileges

  http://pubs.opengroup.org/onlinepubs/9699919799/functions/utime.html

Therefore, just having group write access to a file causes EPERM at
applying os.utime() on it (e.g. working on the repository shared by
group access permission).

This patch adds class filestat utility function avoidamgig() to avoid
file stat ambiguity but skip it if EPERM.

It is reasonable to always ignore EPERM, because utime(2) causes EPERM
only in the case described above (EACCES is used only for utime(2)
with NULL).

running: init test1
result: None
running: add foo
result: 0
running: commit -m commit1 -d 2000-01-01 foo
result: None
running: commit -m commit2 -d 2000-01-02 foo
result: None
running: log -r 0
changeset:   0:0e4634943879
user:        test
date:        Sat Jan 01 00:00:00 2000 +0000
summary:     commit1

result: None
running: log -r tip
changeset:   1:45589e459b2e
tag:         tip
user:        test
date:        Sun Jan 02 00:00:00 2000 +0000
summary:     commit2

result: None