Move PATH set earlier

Checking the logs for a f20 run you'll see

---
 + ./safe-devstack-vm-gate-wrap.sh
 sudo: service: command not found
 22 Jul 21:24:41 ntpdate[1551]: adjust time ...
 sudo: service: command not found
---

We already went through this path issue with [1] so just move it
earlier before anything runs

[1] https://review.openstack.org/#/c/91655/

Change-Id: Ie6bd27342b0ba0f0fba0a1d3695f108128d4366e

devstack-vm-gate-wrap.sh

@@ -25,6 +25,9 @@
 GIT_BASE=${GIT_BASE:-https://git.openstack.org}
 GIT_BRANCH=${GIT_BRANCH:-master}
 
+# sshd may have been compiled with a default path excluding */sbin
+export PATH=$PATH:/usr/local/sbin:/usr/sbin
+
 source $WORKSPACE/devstack-gate/functions.sh
 
 start_timer
@@ -93,9 +96,6 @@ export BASE=/opt/stack
 # The URL from which to fetch ZUUL references
 export ZUUL_URL=${ZUUL_URL:-http://zuul.openstack.org/p}
 
-# sshd may have been compiled with a default path excluding */sbin
-export PATH=$PATH:/usr/local/sbin:/usr/sbin
-
 # Set this variable to skip updating the devstack-gate project itself.
 # Useful in development so you can edit scripts in place and run them
 # directly.  Do not set in production.