1--- a/src/zc/buildout/buildout.py 2017-08-18 10:06:24.946428977 +0300
2+++ b/src/zc/buildout/buildout.py 2017-08-18 10:08:49.115613364 +0300
3@@ -382,6 +382,10 @@
4 if k not in versions
5 ))
6
7+ # Override versions with available (nix) system packages
8+ for dist in pkg_resources.working_set:
9+ versions[dist.project_name] = SectionKey(dist.version, dist.location)
10+
11 # Absolutize some particular directory, handling also the ~/foo form,
12 # and considering the location of the configuration file that generated
13 # the setting as the base path, falling back to the main configuration
14--- a/src/zc/buildout/easy_install.py 2017-08-18 10:06:24.948428980 +0300
15+++ b/src/zc/buildout/easy_install.py 2017-08-18 10:07:37.462521740 +0300
16@@ -321,6 +321,12 @@
17
18 def _satisfied(self, req, source=None):
19 dists = [dist for dist in self._env[req.project_name] if dist in req]
20+ try:
21+ dists = ([dist for dist in dists
22+ if dist.precedence == pkg_resources.DEVELOP_DIST]
23+ + [pkg_resources.get_distribution(req.project_name)])
24+ except pkg_resources.DistributionNotFound:
25+ pass
26 if not dists:
27 logger.debug('We have no distributions for %s that satisfies %r.',
28 req.project_name, str(req))