[fixup] Ignore ${:_profile_base_location_} for reinstall

Fixup "[fixup] Ignore _profile_base_location_ when computing signatures"
Fixup "[feat] Support ${:_profile_base_location_}"

Do not reinstall a section just because its ${:_profile_base_location_}
changed. This is coherent with ignoring ${:_profile_base_location_} for
part signatures.

src/zc/buildout/buildout.py

@@ -939,9 +939,9 @@ class Buildout(DictMixin):
                 if not uninstall_missing:
                     continue
             else:
-                old_options = installed_part_options[part].copy()
+                old_options = installed_part_options[part].normalize()
                 installed_files = old_options.pop('__buildout_installed__')
-                new_options = self.get(part).copy()
+                new_options = self.get(part).normalize()
                 if old_options == new_options:
                     # The options are the same, but are all of the
                     # installed files still there?  If not, we should
@@ -1737,8 +1737,14 @@ class Options(DictMixin):
             self.buildout._parts.append(name)
 
         m = md5()
-        # _profile_base_location_ is ignored in signatures, so that two sections
-        # at different URLs can have same signature
+        for key, value in self._iteritems_normalized():
+            m.update(('%r\0%r\0' % (key, value)).encode())
+        self.items_signature = '%s:%s' % (name, m.hexdigest())
+
+    def _iteritems_normalized(self):
+        # _profile_base_location_ is ignored in signatures and when comparing
+        # options, so that two sections at different URLs can have the same
+        # signature and compare equal
         _profile_base_location_ = self.get('_profile_base_location_')
         # access values through .get() instead of .items() to detect unused keys
         for key in sorted(self.keys()):
@@ -1747,8 +1753,10 @@ class Options(DictMixin):
             value = self._data.get(key, self._cooked.get(key, self._raw.get(key)))
             if _profile_base_location_:
                 value = value.replace(_profile_base_location_, '${:_profile_base_location_}')
-            m.update(('%r\0%r\0' % (key, value)).encode())
-        self.items_signature = '%s:%s' % (name, m.hexdigest())
+            yield key, value
+
+    def normalize(self):
+        return dict(self._iteritems_normalized())
 
     def _do_extend_raw(self, name, data, doing):
         if name == 'buildout':