pgsql: pgflex: propagate environment to flex subprocess

pgflex: propagate environment to flex subprocess

Python's subprocess.run docs say that if the env argument is not None,
it will be used "instead of the default behavior of inheriting the
current process’ environment".  However, the environment should be
preserved, only adding FLEX_TMP_DIR to it.

Author: Javier Maestro <jjmaestro@ieee.org>
Discussion:
https://www.postgresql.org/message-id/flat/CABvji06GUpmrTqqiCr6_F9vRL2-JUSVAh8ChgWa6k47FUCvYmA%40mail.gmail.com

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/40a96cd1484fdf3ab57e8cb7b09767ec7a7f73b1

Modified Files
--------------
src/tools/pgflex | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)