Re: [PATCH di/fast-import-deltified-tree] Windows: define S_ISUID properly

Dmitry Ivankov [off-list ref] writes:

Johannes Sixt <j.sixt <at> viscovery.net> writes:

quoted

From: Johannes Sixt <j6t <at> kdbg.org>

8fb3ad76 (fast-import: prevent producing bad delta) introduced the first
use of S_ISUID. Since before this commit the value was irrelevant, we had
only a dummy definition in mingw.h. But beginning with this commit the
macro must expand to a reasonable value. Make it so.
 #define S_ISVTX 0
...

Ow, it's awkward that the issue was discussed in [1] but slipped and nobody 
noticed, especially me being a patch sender.

If we choose patch from [1] I'd also change a comment to smth like
/* 
 * We abuse the 04000 bit on directories to mean "do not delta".
 * It is a S_ISUID bit on setuid platforms and an unused bit on
 * non-setuid platforms supported in git. In either case git ignores
 * the bit, so it's safe to abuse it locally.
 */

[1] http://thread.gmane.org/gmane.comp.version-control.git/179223/focus=179762

I think that the fix from Jonathan to stop abusing S_ISUID is much more
preferrable; the Windows platform shouldn't have to worry about this.

And it would be even better to use a value that does not overlap with the
usual bits for do-not-delta bit if possible.