try fixing null git ref

Author: matteius

pipenv/utils/resolver.py

@@ -27,7 +27,7 @@
 from pipenv.patched.pip._vendor.packaging.utils import canonicalize_name
 from pipenv.project import Project
 from pipenv.utils import console, err
-from pipenv.utils.dependencies import normalize_vcs_url
+from pipenv.utils.dependencies import determine_vcs_revision_hash, normalize_vcs_url
 from pipenv.utils.fileutils import create_tracked_tempdir
 from pipenv.utils.requirements import normalize_name
 
@@ -604,16 +604,12 @@ def clean_skipped_result(
             vcs = ireq.link.scheme.split("+", 1)[0]
 
             # Try to get reference from multiple sources
-            ref = None
-            if ireq.link.egg_fragment:
-                ref = ireq.link.egg_fragment
-            elif entry.get("ref"):
-                ref = entry["ref"]
-            elif hasattr(ireq.link, "ref"):
-                ref = ireq.link.ref
+            ref = determine_vcs_revision_hash(ireq, vcs, ireq.link)
 
             if ref:
                 entry["ref"] = ref
+            elif ireq.link.hash:
+                entry["ref"] = ireq.link.hash
 
             # Ensure VCS URL is present
             if vcs not in entry: