pgsql: Try again to make pg_isolation_regress work its build directory.

Try again to make pg_isolation_regress work its build directory.

We can't search for the isolationtester binary until after we've set
up the environment, because otherwise when find_other_exec() tries
to invoke it with the -V option, it might fail for inability to
locate a working libpq.  So postpone that step.

Andres Freund

Branch
------
master

Details
-------
http://git.postgresql.org/pg/commitdiff/061b88c732952c59741374806e1e41c1ec845d50

Modified Files
--------------
src/test/isolation/isolation_main.c |   33 ++++++++++++++++++++++++++-------
1 file changed, 26 insertions(+), 7 deletions(-)