Add 3 edits suggested from @epicfaace

Lib/test/test_urlparse.py

@@ -394,6 +394,10 @@ class UrlParseTestCase(unittest.TestCase):
         # Test for issue9721
         self.checkJoin('http://a/b/c/de', ';x','http://a/b/c/;x')
 
+        # Tests for issue39799: no base fragment
+        self.checkJoin('http://a/b#f', '', 'http://a/b')
+        self.checkJoin('http://a/b/#f', 'g', 'http://a/b/g')
+
     def test_urljoins(self):
         self.checkJoin(SIMPLE_BASE, 'g:h','g:h')
         self.checkJoin(SIMPLE_BASE, 'http:g','http://a/b/c/g')
@@ -449,9 +453,6 @@ class UrlParseTestCase(unittest.TestCase):
         # issue 23703: don't duplicate filename
         self.checkJoin('a', 'b', 'b')
 
-        # issue 39799: no base fragment (not compatible with RFC1808)
-        self.checkJoin('http://a/b#f', '', 'http://a/b')
-
     def test_RFC2732(self):
         str_cases = [
             ('http://Test.python.org:5432/foo/', 'test.python.org', 5432),

Misc/NEWS.d/next/Library/2020-02-29-20-44-36.bpo-39799.qTHOaP.rst

@@ -1,3 +1,2 @@
-Fix ``urllib.parse.urljoin``
-when ``base`` has fragment and ``url`` is blank
-(Returns ``base`` without fragment, not ``base`` entirely).
+Fix ``urllib.parse.urljoin``.
+In RFC 3986, ``base``'s fragment is always discarded.