Re: [PATCH/RFC] recv_sideband: Band #2 always goes to stderr

Johannes Sixt [off-list ref] writes:

All data producers and data consumers *in git* use band #2 to transport
error messages and progress report.

Correct; I wrote that in the big comment at the beginning of sideband.c.

Of course we could enhance the protocol to use more bands as needed.  #2
and #3 have their own meanings and they both map well to "send to stderr".