The pipe's FDs got inherited by ssh and it did something that kept them
open even once it exited. Probably involving passing them on to the ssh
mux daemon.
Set close on exec, and all is well.
Kept Annex.Ssh not using processTranscript even though it no longer
hangs when it does use it, just because processTranscript is overkill
there.
This commit was supported by the NSF-funded DataLad project.
Fix race condition in ssh warmup that caused git-annex to get stuck and
never process some while when run with high levels of concurrency.
So far, I've isolated the problem to processTranscript, which hangs
reading output from ssh in this situation. I don't yet understand why
processTranscript behaves that way.
Since here we don't care about the ssh output, and only want to /dev/null
it, changed to not use processTranscript, avoiding its problem.
This commit was supported by the NSF-funded DataLad project.
