Fix regression in `lb-run --path-to-project`

this should fix the regression reported by @rmatev in !242 (comment 803854)

LbConfiguration/python/LbConfiguration/SP2/script.py

@@ -279,8 +279,9 @@ class SP2(EnvConfig.Script):
                 self.allow_empty_version = True
                 self.version = DEFAULT_VERSION
         if self.opts.platform is None:
-            self.opts.platform = ('best' if self.project.lower() == 'lhcbdirac'
-                                  else self._default_platform)
+            self.opts.platform = (
+                'best' if str(self.project.lower()) == 'lhcbdirac'
+                else self._default_platform)
 
     def _add_ext_dir_to_env(self, path):
         def prepend(k, v):