Fix Issue9721 - urljoin behavior when the relative url starts with ';'
diff --git a/Lib/test/test_urlparse.py b/Lib/test/test_urlparse.py
index 73e4de5..f9f97b1 100644
--- a/Lib/test/test_urlparse.py
+++ b/Lib/test/test_urlparse.py
@@ -327,6 +327,9 @@
         #self.checkJoin(RFC3986_BASE, 'http:g','http:g') # strict parser
         self.checkJoin(RFC3986_BASE, 'http:g','http://a/b/c/g') #relaxed parser
 
+        # Test for issue9721
+        self.checkJoin('http://a/b/c/de', ';x','http://a/b/c/;x')
+
     def test_urljoins(self):
         self.checkJoin(SIMPLE_BASE, 'g:h','g:h')
         self.checkJoin(SIMPLE_BASE, 'http:g','http://a/b/c/g')
diff --git a/Lib/urllib/parse.py b/Lib/urllib/parse.py
index eedd071..42f8193 100644
--- a/Lib/urllib/parse.py
+++ b/Lib/urllib/parse.py
@@ -411,14 +411,9 @@
     if path[:1] == '/':
         return _coerce_result(urlunparse((scheme, netloc, path,
                                           params, query, fragment)))
-    if not path:
+    if not path and not params:
         path = bpath
-        if not params:
-            params = bparams
-        else:
-            path = path[:-1]
-            return _coerce_result(urlunparse((scheme, netloc, path,
-                                              params, query, fragment)))
+        params = bparams
         if not query:
             query = bquery
         return _coerce_result(urlunparse((scheme, netloc, path,