In pg_upgrade, issue proper error message when we can't open PG_VERSION.
Backpatch to 9.2.
Branch------master
Details-------http://git.postgresql.org/pg/commitdiff/a9701a1d7df8c7a088ed7c37316fe4118a507015
Modified Files--------------contrib/pg_upgrade/server.c | 2 +-1 files changed, 1 insertions(+), 1 deletions(-)
