fixup! Support ${:_profile_base_location_}.

src/zc/buildout/buildout.py

@@ -1886,15 +1886,11 @@ def _open(base, filename, seen, dl_options, override, downloaded):
             filename)
 
     # find and expose _profile_base_location_
-    for section, value in result.items():
-        _profile_base_location_ = None
-        for k,v in value.items():
-          if '${:_profile_base_location_}' in v:
-            _profile_base_location_ = base
-          if _profile_base_location_ is not None:
+    for section in result.values():
+        for value in section.values():
+            if '${:_profile_base_location_}' in value:
+                section['_profile_base_location_'] = base
                 break
-        if _profile_base_location_ is not None:
-          value['_profile_base_location_'] = _profile_base_location_
 
     result = _annotate(result, filename)