Suppress invalid versions when parsing in package_index. They will st…

…ill be allowed for now as long as DeprecationWarnings aren't treated as errors.

setuptools/package_index.py

@@ -21,7 +21,7 @@
 from pkg_resources import (
     CHECKOUT_DIST, Distribution, BINARY_DIST, normalize_path, SOURCE_DIST,
     Environment, find_distributions, safe_name, safe_version,
-    to_filename, Requirement, DEVELOP_DIST, EGG_DIST,
+    to_filename, Requirement, DEVELOP_DIST, EGG_DIST, parse_version,
 )
 from distutils import log
 from distutils.errors import DistutilsError
@@ -294,6 +294,14 @@ def __init__(
         self.to_scan = []
         self.opener = urllib.request.urlopen
 
+    def add(self, dist):
+        # ignore invalid versions
+        try:
+            parse_version(dist.version)
+        except Exception:
+            return
+        return super().add(dist)
+
     # FIXME: 'PackageIndex.process_url' is too complex (14)
     def process_url(self, url, retrieve=False):  # noqa: C901
         """Evaluate a URL as a possible download, and maybe retrieve it"""