diff -r c84a0b35999a Lib/test/test_urlparse.py
--- a/Lib/test/test_urlparse.py	Thu Mar 19 15:24:27 2015 +0200
+++ b/Lib/test/test_urlparse.py	Thu Mar 19 08:03:55 2015 -0700
@@ -391,6 +391,9 @@
         self.checkJoin('http://a/b/c/d/e/', '../../f/g', 'http://a/b/c/f/g')
         self.checkJoin('http://a/b/', '../../f/g/', 'http://a/f/g/')
 
+        # issue23703
+        self.checkJoin('a', 'b', 'b')
+
     def test_RFC2732(self):
         str_cases = [
             ('http://Test.python.org:5432/foo/', 'test.python.org', 5432),
diff -r c84a0b35999a Lib/urllib/parse.py
--- a/Lib/urllib/parse.py	Thu Mar 19 15:24:27 2015 +0200
+++ b/Lib/urllib/parse.py	Thu Mar 19 08:03:55 2015 -0700
@@ -445,8 +445,10 @@
         segments = base_parts + path.split('/')
         # filter out elements that would cause redundant slashes on re-joining
         # the resolved_path
-        segments = segments[0:1] + [
-            s for s in segments[1:-1] if len(s) > 0] + segments[-1:]
+        segs = segments[0:1] + [s for s in segments[1:-1] if s]
+        if len(segments) > 1:
+            segs.append(segments[-1])
+        segments = segs
 
     resolved_path = []