Search another path for etc/tempest

sys.prefix is gotten from the path which pyconfig.h is installed under.
Some envs contain it under /usr/include, not /user/local/include.
Then prefix becomes /usr on such envs.
However, etc/tempest is installed under /usr/local and the original
path logic mismatches.

This patch adds a workaround for such envs.

Closes-Bug: #1573873

Change-Id: I1ce3e639d77ab2d0e786fea5aaca574653e48673
diff --git a/tempest/cmd/init.py b/tempest/cmd/init.py
index 6fb4e5b..d8d9d7c 100644
--- a/tempest/cmd/init.py
+++ b/tempest/cmd/init.py
@@ -66,7 +66,16 @@
         # '[sys.prefix]/etc/tempest'
         return global_conf_dir
     else:
-        return os.path.join(prefix, 'etc/tempest')
+        conf_dir = os.path.join(prefix, 'etc/tempest')
+        if os.path.isdir(conf_dir):
+            return conf_dir
+        else:
+            # NOTE: The prefix is gotten from the path which pyconfig.h is
+            # installed under. Some envs contain it under /usr/include, not
+            # /user/local/include. Then prefix becomes /usr on such envs.
+            # However, etc/tempest is installed under /usr/local and the bove
+            # path logic mismatches. This is a workaround for such envs.
+            return os.path.join(prefix, 'local/etc/tempest')
 
 
 class TempestInit(command.Command):