tests/test-mq-qpush-fail.out

dirstate: ignore symlinks when fs cannot handle them (issue1888)

When the filesystem cannot handle the executable bit, we currently
ignore it completely when looking for modified files. Similarly, it is
impossible to set or clear the bit when the filesystem ignores it.

This patch makes Mercurial treat symbolic links the same way.

Symlinks are a little different since they manifest themselves as
small files containing a filename (the symlink target). On Windows,
these files show up as regular files, and on Linux and Mac they show
up as real symlinks.

Issue1888 presents a case where the symlink files are better ignored
from the Windows side. A Linux client creates symlinks in a working
copy which is shared over a network between Linux and Windows clients.

The Samba server is helpful and defererences the symlink when the
Windows client looks at it. This means that Mercurial on the Windows
side sees file content instead of a file name in the symlink, and
hence flags the link as modified. Ignoring the change would be much
more helpful, similarly to how Mercurial does not report any changes
when executable bits are ignored in a checkout on Windows.

An initial checkout of a symbolic link on a file system that cannot
handle symbolic links will still result in a regular file containing
the target file name as its content. Sharing such a checkout with a
Linux client will not turn the file into a symlink automatically, but
'hg revert' can fix that. After the revert, the Windows client will
see the correct file content (provided by the Samba server when it
follows the link on the Linux side) and otherwise ignore the change.

Running 'hg perfstatus' 10 times gives these results:

  Before:          After:
  min: 0.544703    min: 0.546549
  med: 0.547592    med: 0.548881
  avg: 0.549146    avg: 0.548549
  max: 0.564112    max: 0.551504

The median time is increased about 0.24%.

adding foo
% test qpush on empty series
no patches in series
popping bad-patch
popping patch2
popping patch1
patch queue now empty
applying patch1
applying patch2
applying bad-patch
transaction abort!
rollback completed
cleaning up working directory...done
abort: decoding near 'é': 'ascii' codec can't decode byte 0xe9 in position 0: ordinal not in range(128)!
changeset:   0:bbd179dfa0a7
tag:         tip
user:        test
date:        Thu Jan 01 00:00:00 1970 +0000
summary:     add foo

% bar should be gone; other unknown/ignored files should still be around
? untracked-file
I .hgignore
C foo
% preparing qpush of a missing patch
no patches applied
applying patch1
now at: patch1
% now we expect the push to fail, but it should NOT complain about patch1
applying patch2
unable to read patch2
now at: patch1
% preparing qpush of missing patch with no patch applied
popping patch1
patch queue now empty
% qpush should fail the same way as below
applying patch1
unable to read patch1