Re: pg_regress breaks on msys

I wrote:
> Ah-hah, so apparently "make install DESTDIR=foo" somehow inserts DESTDIR
> after that instead of before it?  What we need is a way to determine the
> paths that make install used ...

AFAICS, the makefiles are just blindly concatenating DESTDIR with bindir
etc, for instance this is how initdb/Makefile installs initdb:
$(INSTALL_PROGRAM) initdb$(X) '$(DESTDIR)$(bindir)/initdb$(X)'

The evidence at hand says that this should produce exactly the same path
string as pg_regress is then using to call initdb.  So the question in
my mind now is how come the "make install" step isn't failing.  For that
matter, this same path-construction technique was used by the
shellscript... so how come it worked before?

It would be simple enough to make pg_regress strip off a drive letter
from the path strings it receives from the Makefile, but I'm not seeing
a principled way to discover that the "/msys/1.0/" part has to go.  How
are the makefiles managing to generate a different value of $(bindir) at
install time than what was passed into pg_regress at build time?
        regards, tom lane