global-jjb to v0.50.0-4-g8285615

This picks up a fix to jenkins-configure-clouds.sh that blocked
change of build minion images.

Signed-off-by: Lott, Christopher (cl778h) <cl778h@att.com>
Change-Id: I7a4859893d1d2b2d0e76f5acc751ed52839e2dbd

diff --git a/global-jjb b/global-jjb
index 0bc70d1..8285615 160000 (submodule)
--- a/global-jjb
+++ b/global-jjb
@@ -1 +1 @@
-Subproject commit 0bc70d1762dc88b90d4f9aa99a2f3bbf2b55b078
+Subproject commit 8285615e111cae15f76eba24e5720068d16e778f