"make test" works again (sort-of) on cygwin.

[Ramsay Jones <ramsay@ramsay1.demon.co.uk>]

Hi *,

Having upgraded to version 1.5.6 (via tarball), I can "make test" once
again, without crashing my machine. (well, it grinds to a halt, so that
I have to pull the power cord, followed by the battery!) I have been
unable to do that since v1.5.3!

I spent many hours (not recently) trying to determine the reason for
the crash, but it seems to be essentially "random gremlins" :-)
However, since I mostly use Linux, I've not been very motivated to
find a solution, particularly when git works fine (touch wood) when
used for real work. (i.e. only "make test" crashes my machine).
Also, as Alex and Shawn have not reported problems, I have assumed
it is something specific to my environment. Dunno.

Anyhow, the "sort-of" in the subject line, relates to the fact that
I am seeing some test failures.  In particular, all tests in
t0004-unwritable.sh and tests 21->24 in t3700-add.sh. All of these
tests involve chmod/permissions ...

I haven't spent too long trying to debug this, but looking at the
first (actually second) test in t0004, I did an strace on git-write-tree.
After wading through the output, it seems that cygwin allows mkdir()
to succeed in the (un-writable) .git/object directory; eg. when
writing the tree object 47d832... it succeeds in making the 47 directory
(which does have write permission) followed by the d832... file.
So I tried this by hand:

    $ mkdir obj
    $ chmod a-w obj
    $ echo file >obj/file
    bash: obj/file: Permission denied
    $ mkdir obj/dir
    $

OK.

[Junio, in the tarball, the test files t5304-prune.sh and
t7610-mergetool.sh do not have the executable bit set]

ATB,

Ramsay Jones