Factorise _compute_part_hash().

src/zc/buildout/buildout.py

@@ -928,6 +928,12 @@ class Buildout(DictMixin):
                 self._logger.warning(
                     "Unexpected entry, %r, in develop-eggs directory.", f)
 
+    def _compute_part_hash(self, part):
+        m = md5()
+        for k, v in sorted(self.get(part).items()):
+            m.update(('%r: %r' % (k, v)).encode())
+        return m.hexdigest()
+
     def _compute_part_signatures(self, parts):
         # Compute recipe signature and add to options
         for part in parts:
@@ -938,10 +944,7 @@ class Buildout(DictMixin):
             req = pkg_resources.Requirement.parse(recipe)
             sig = sorted(set(_dists_sig(pkg_resources.working_set.resolve([req]))))
             for dependency in sorted(getattr(options, '_dependency', [])):
-                m = md5()
-                for k, v in sorted(self.get(dependency).items()):
-                    m.update(('%r: %r' % (k, v)).encode())
-                dependency_hash = m.hexdigest()
+                dependency_hash = self._compute_part_hash(dependency)
                 sig.append('%s:%s' % (dependency, dependency_hash))
             options['__buildout_signature__'] = ' '.join(sig)