Don't log file contents when loading dynamic layouts

These files can get quite large.

Change-Id: I7d6b25f6767291260d567f9ff69735c1e27416c5
diff --git a/zuul/manager/__init__.py b/zuul/manager/__init__.py
index 98c7350..b94b8a5 100644
--- a/zuul/manager/__init__.py
+++ b/zuul/manager/__init__.py
@@ -435,7 +435,7 @@
         loader = zuul.configloader.ConfigLoader()
 
         build_set = item.current_build_set
-        self.log.debug("Load dynamic layout with %s" % build_set.files)
+        self.log.debug("Loading dynamic layout")
         try:
             # First parse the config as it will land with the
             # full set of config and project repos.  This lets us
@@ -456,13 +456,11 @@
                 include_config_projects=False)
         except zuul.configloader.ConfigurationSyntaxError as e:
             self.log.info("Configuration syntax error "
-                          "in dynamic layout %s" %
-                          build_set.files)
+                          "in dynamic layout")
             item.setConfigError(str(e))
             return None
         except Exception:
-            self.log.exception("Error in dynamic layout %s" %
-                               build_set.files)
+            self.log.exception("Error in dynamic layout")
             item.setConfigError("Unknown configuration error")
             return None
         return layout