Re: pg_ctl/pg_rewind tests vs. slow AIX buildfarm members

I wrote:
> Andres Freund <andres(at)anarazel(dot)de> writes:
>> I'don't like adding a couple seconds of test runtime for the benefit of
>> very slow platforms.

> Me either. This is the first time I've seen an indication that the
> start_postmaster change mentioned in the comment is actually important
> for production use, rather than just being cleanup. I think we ought
> to just fix it. I'm willing to take care of the Unix side if someone
> will explain how to change the Windows side.

Attached is a draft patch for this. I think it's fine for Unix (unless
someone wants to object to relying on "/bin/sh -c"), but I have no idea
whether it works for Windows. The main risk is that if CMD.EXE runs
the postmaster as a subprocess rather than overlaying itself a la shell
"exec", the PID we'd get back would apply only to CMD.EXE not to the
eventual postmaster. If so, I do not know how to fix that, or whether
it's fixable at all.

Note that this makes the test case in question fail reliably, which is
reasonable behavior IMO so I just changed the test.

If this does (or can be made to) work on Windows, I'd propose applying
it back to 9.2, where the current coding came in.

regards, tom lane