Re: message string fixes

I wrote:
> It looks to me like RS_isRegis() needs to be tightened up a bit anyway:
> it will accept "^foo" which is valid regex but not valid regis, leading
> to an error being thrown which is not what we want.

I experimented with this and verified that the error could be reached
with a hacked-up affix file.

> If we tighten it to exactly match what RS_compile() will take ... say
> by using the same state-machine logic ... then indeed the ereports
> are internal and can be demoted to elog's. If we make them elogs then
> ISTM they ought to keep saying regis, just so we know where to look
> if they ever do fail ;-)

Patch committed along these lines.

regards, tom lane