[3.13] gh-145831: email.quoprimime: decode() leaves stray \r when eol='\r\n' (GH-145832) (#148311)

decoded[:-1] only strips one character, leaving a stray \r when eol
is two characters. Fix: decoded[:-len(eol)].
(cherry picked from commit 1a0edb1)

Co-authored-by: Stefan Zetzsche <120379523+stefanzetzsche@users.noreply.github.com>

Author: miss-islington

Lib/email/quoprimime.py

@@ -272,7 +272,7 @@ def decode(encoded, eol=NL):
                 decoded += eol
     # Special case if original string did not end with eol
     if encoded[-1] not in '\r\n' and decoded.endswith(eol):
-        decoded = decoded[:-1]
+        decoded = decoded[:-len(eol)]
     return decoded
 
 

Lib/test/test_email/test_email.py

@@ -4802,6 +4802,15 @@ def test_decode_soft_line_break(self):
     def test_decode_false_quoting(self):
         self._test_decode('A=1,B=A ==> A+B==2', 'A=1,B=A ==> A+B==2')
 
+    def test_decode_crlf_eol_no_trailing_newline(self):
+        self._test_decode('abc', 'abc', eol='\r\n')
+
+    def test_decode_crlf_eol_multiline_no_trailing_newline(self):
+        self._test_decode('a\r\nb', 'a\r\nb', eol='\r\n')
+
+    def test_decode_crlf_eol_with_trailing_newline(self):
+        self._test_decode('abc\r\n', 'abc\r\n', eol='\r\n')
+
     def _test_encode(self, body, expected_encoded_body, maxlinelen=None, eol=None):
         kwargs = {}
         if maxlinelen is None:

Misc/NEWS.d/next/Library/2026-03-11-15-09-52.gh-issue-145831._sW94w.rst

@@ -0,0 +1,2 @@
+Fix :func:`!email.quoprimime.decode` leaving a stray ``\r`` when
+``eol='\r\n'`` by stripping the full *eol* string instead of one character.