Investigate timeouts on openssh-rs

[xd009642]

https://github.com/jonhoo/openssh-rs/pull/26#issuecomment-1025285977 @jonhoo

Investigate the timeouts on openssh-rs, taking a look via the tarpaulin debug trace file it looks like each timed out test had a "vfork, but not each vfork has a corresponding fork event, then they all got a SIGCHLD stop and a continue and the test ended after that - which is probably the rustc test runner killing them :thinking:. Also there's a long running tid which gets some TryContinue's (so either tarpaulin got an event it's not sure about or it's a known fallible-continue).

Some pictures attached with text underneath about them

This is fairly early on, showing the long running branch with the TryContinue's every now and then. As well as one test completing and another running fine.

Another long running TryContinue but this one doesn't reappear, it happens kinda middle of the run... Bit odd we never hear from it again :thinking:

The vforks, only 11707 ends up with a fork child... Others strangely don't

End of the vforks and the final events tarpaulin gets

[xd009642]

Also attaching the traces in case I lose the file, easy enough to regenerate but don't yet know how consistent the behaviour is tarpaulin-run.zip