Johannes Sixt wrote:

Am 30.12.19 um 19:06 schrieb Jonathan Nieder:

quoted

                                                                   when
errno is meaningful for a function for a given return value, the usual
convention is

 (1) it *always* sets errno for errors, not conditionally

You seem to understand that errno isn't set somewhere where it should be
set.

On the contrary: this caller is using errno as an error *indicator*
instead of a way of *distinguishing* between errors (or to put it
another way, this caller is treating `errno == 0` as a meaningful
condition).  This means the calling code is buggy.

[...]

quoted

Do you have more details about the case where read_object is expected
to produce errno == 0?  I'm wondering whether we forgot to set 'errno
= ENOENT' explicitly somewhere.

I don't think that forgetting to set ENOENT is the problem.

It happens reproducibly in test 5 of t0410-partial-clone:

Thanks, will try it out.