--- a/mercurial/templatefilters.py	Tue Mar 22 11:22:09 2022 -0400
+++ b/mercurial/templatefilters.py	Thu Mar 24 15:41:29 2022 -0700
@@ -269,7 +269,7 @@
 def firstline(text):
     """Any text. Returns the first line of text."""
     try:
-        return text.splitlines(True)[0].rstrip(b'\r\n')
+        return text.splitlines()[0]
     except IndexError:
         return b''