Re: [PATCH 2/3] receive-pack: send pack-processing stderr over sideband

> Receive-pack invokes either unpack-objects or index-pack to
> handle the incoming pack. However, we do not redirect the
> stderr of the sub-processes at all, so it is never seen by
> the client. From the initial thread adding sideband support,
> which is here:
>
>   http://thread.gmane.org/gmane.comp.version-control.git/139471
>
> it is clear that some messages are specifically kept off the
> sideband (with the assumption that they are of interest only
> to an administrator, not the client). The stderr of the
> subprocesses is mentioned in the thread, but it's unclear if
> they are included in that group, or were simply forgotten.
>
> However, there are a few good reasons to show them to the
> client:
>
>   1. In many cases, they are directly about the incoming
>      packfile (e.g., fsck warnings with --strict, corruption
>      in the packfile, etc). Without these messages, the
>      client just gets "unpacker error" with no extra useful
>      diagnosis.
>
>   2. No matter what the cause, we are probably better off
>      showing the errors to the client. If the client and the
>      server admin are not the same entity, it is probably
>      much easier for the client to cut-and-paste the errors
>      they see than for the admin to try to dig them out of a
>      log and correlate them with a particular session.

>   3. Users of the ssh transport typically already see these
>      stderr messages, as the remote's stderr is copied
>      literally by ssh. This brings other transports (http,
>      and push-over-git if you are crazy enough to enable it)
>      more in line with ssh. As a bonus for ssh users,
>      because the messages are now fed through the sideband
>      and printed by the local git, they will have "remote:"
>      prepended and be properly interleaved with any local
>      output to stderr.
>
> Signed-off-by: Jeff King <peff@peff.net>
> ---