plz watch: --run flag is broken

[katzdm]

Running plz watch --run <TARGET>does not run the executable.

[katzdm]

Hey @peterebden , thanks for the quick turnaround on this! There's a small problem with your change - After killing the plz watch invocation with CTRL+C, the process(es) started by plz (i.e. the binary targets) continue to run.

This was especially problematic since the binary I'm testing with is a webserver, so the next time I ran plz watch --run //example_service, the program couldn't start because port 8080 was already in use (by the abandoned process). kill -9 did the trick, but I'm sure plz can be smart enough to handle the signal and kill the process :)

[peterebden]

Yup fair - to be honest the current implementation isn't great for persistent processes (it really needs to kill them when changes happen). Was thinking about that as I wrote that fix but didn't have time for it then.

[peterebden]

594a0ec should improve this considerably. Somewhat surprisingly it now seems to terminate subprocesses although I've not done anything explicit for that.