From 980437050ef355905fe026c1a5d0e2e8e32fabd0 Mon Sep 17 00:00:00 2001
From: navrkald <navrkald@gmail.com>
Date: Tue, 16 Aug 2022 13:42:00 +0200
Subject: [PATCH] Fixes #920. Don't replace unserscores with hyphens in
 distribution name.

---
 tests/test_package.py | 1 +
 twine/package.py      | 4 ++--
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/tests/test_package.py b/tests/test_package.py
index 0b883da3..9ac47fd8 100644
--- a/tests/test_package.py
+++ b/tests/test_package.py
@@ -121,6 +121,7 @@ def test_package_signed_name_is_correct():
         (string.digits, string.digits),
         (string.punctuation, "-.-"),
         ("mosaik.SimConfig", "mosaik.SimConfig"),
+        ("package_name", "package_name"),
         ("mosaik$$$$.SimConfig", "mosaik-.SimConfig"),
     ],
 )
diff --git a/twine/package.py b/twine/package.py
index 3ca074fe..7caad349 100644
--- a/twine/package.py
+++ b/twine/package.py
@@ -51,12 +51,12 @@
 def _safe_name(name: str) -> str:
     """Convert an arbitrary string to a standard distribution name.
 
-    Any runs of non-alphanumeric/. characters are replaced with a single '-'.
+    Any runs of non-alphanumeric/./_ characters are replaced with a single '-'.
 
     Copied from pkg_resources.safe_name for compatibility with warehouse.
     See https://github.com/pypa/twine/issues/743.
     """
-    return re.sub("[^A-Za-z0-9.]+", "-", name)
+    return re.sub("[^A-Za-z0-9._]+", "-", name)
 
 
 class PackageFile: