Merge pull request #1045 from eschnett/eschnett/openmpi-verbs-usr

Do not pass "/usr" or "/usr/local" as path to configure

var/spack/repos/builtin/packages/openmpi/package.py

@@ -142,7 +142,7 @@ def install(self, spec, prefix):
         ])
         if '+verbs' in spec:
             path = _verbs_dir()
-            if path is not None:
+            if path is not None and path not in ('/usr', '/usr/local'):
                 config_args.append('--with-%s=%s' % (self.verbs, path))
             else:
                 config_args.append('--with-%s' % self.verbs)