bug#42538: 28.0.50; tramp-test35-remote-path test timing out on macOS

[Philipp Stephani]

Am Fr., 31. Juli 2020 um 17:02 Uhr schrieb Philipp Stephani
<p.stephani2@gmail.com>:
>
> >
> > > However, now it looks like tramp-test29-start-file-process is timing 
> > > out...
> >
> > Strange. The patch doesn't touch anything which is relevant for
> > tramp-test29-start-file-process, AFAICT. OK, same procedure as very
> > year: apply the appended patch to tramp-tests.el, and rerun the
> > test. The debug buffer shall tell us more.
> >
>
>
> An update on this: I messed up the test numbers, it's actually the
> test tramp-test28-process-file that times out. I've tried to apply a
> similar patch (increasing the log level and using with-timeout), but
> apparently it's stuck enough that none of the signals except SIGKILL
> work any more. Here's the console output:
>
> HOME=/nonexistent EMACSLOADPATH= LC_ALL=C
> EMACS_TEST_DIRECTORY=/Users/p/Entwicklung/Emacs/master/test
> "../src/emacs" --module-assertions --no-init-file --no-site-file
> --no-site-lisp -L ":."  \
>   -l ert  -l lisp/net/tramp-tests.el \
>   --batch --eval '(ert-run-tests-batch-and-exit (quote
> tramp-test28-process-file))'
> Running 1 tests (2020-07-31 16:09:42+0200, selector 
> `tramp-test28-process-file')
> Tramp: Sending command `exec sh -i'
> Tramp: Found remote shell prompt on `p'
> timeout: sending signal TERM to command ‘make’
>
> ^Ctimeout: sending signal INT to command ‘make’
> ^\timeout: sending signal QUIT to command ‘make’
>
> make[1]: *** [lisp/net/tramp-tests.log] Killed: 9
> make: *** [lisp/net/tramp-tests] Quit: 3

Emacs here is stuck waiting for the process "bash -c 'kill -17 $$'" to
terminate. However, signal 17 is SIGSTOP on macOS, so this process can
never terminate. This might be caused by the code in
`tramp-get-signal-strings' assuming that signal 19 is SIGSTOP.