Don't mix declaration and set of locals

Ia0957b47187c3dcadd46154b17022c4213781112 proposes to have bashate
find instances of setting a local value.  The issue is that "local"
always returns 0, thus hiding any failure in the commands running to
set the variable.

This is an automated replacement of such instances

Depends-On: I676c805e8f0401f75cc5367eee83b3d880cdef81
Change-Id: I9c8912a8fd596535589b207d7fc553b9d951d3fe
diff --git a/lib/tempest b/lib/tempest
index f4d0a6d..e7ea429 100644
--- a/lib/tempest
+++ b/lib/tempest
@@ -372,7 +372,8 @@
     # Compute Features
     # Run ``verify_tempest_config -ur`` to retrieve enabled extensions on API endpoints
     # NOTE(mtreinish): This must be done after auth settings are added to the tempest config
-    local tmp_cfg_file=$(mktemp)
+    local tmp_cfg_file
+    tmp_cfg_file=$(mktemp)
     cd $TEMPEST_DIR
     tox -revenv -- verify-tempest-config -uro $tmp_cfg_file