Fix venv for ./run_tests.sh -p

Currently just running pep8 with ./run_test.sh -p is not
using the venv because the wrapper definition was occurring
after tools/hacking.py was run. This moves the pep8 check to
after the venv setup to fix this issue.

Change-Id: Ie9fd2a427d8e8875d0cb0db885ea442b2d29ae73
diff --git a/run_tests.sh b/run_tests.sh
index 344f3ff..0df8a99 100755
--- a/run_tests.sh
+++ b/run_tests.sh
@@ -84,11 +84,6 @@
 
 NOSETESTS="nosetests $noseargs"
 
-if [ $just_pep8 -eq 1 ]; then
-    run_pep8
-    exit
-fi
-
 if [ $never_venv -eq 0 ]
 then
   # Remove the virtual environment if --force used
@@ -115,6 +110,11 @@
   fi
 fi
 
+if [ $just_pep8 -eq 1 ]; then
+    run_pep8
+    exit
+fi
+
 run_tests || exit
 
 if [ -z "$noseargs" ]; then