[fix] Sign .dist-info dists with version

This avoids rebootstrap changing the signature of zc.buildout when
the package is in sites-packages for the initial Python version but
not in the sites-packages of the target Python (when it's not the
same Python)

src/zc/buildout/buildout.py

@@ -2174,7 +2174,8 @@ def _dists_sig(dists):
         seen.add(dist)
         location = dist.location
         if (dist.precedence == pkg_resources.DEVELOP_DIST
-            and location != zc.buildout.easy_install.python_lib):
+            and location != zc.buildout.easy_install.python_lib
+            and not isinstance(dist, pkg_resources.DistInfoDistribution)):
             result.append(dist.project_name + '-' + _dir_hash(location))
         else:
             result.append(dist.project_name + '-' + dist.version)