Fix regression decoding query string params in join urls

#1039 introduced a regression in decoding query
string params

tests/test_url.py

@@ -1853,3 +1853,32 @@ def test_requoting():
     u = URL("http://127.0.0.1/?next=http%3A//example.com/")
     assert u.raw_query_string == "next=http://example.com/"
     assert str(u) == "http://127.0.0.1/?next=http://example.com/"
+
+
+@pytest.mark.xfail
+def test_join_query_string():
+    """Test that query strings are correctly joined."""
+    original = URL("http://127.0.0.1:62869")
+    path_url = URL(
+        "/api?start=2022-03-27T14:05:00%2B03:00&end=2022-03-27T16:05:00%2B03:00"
+    )
+    assert original.query_string == ""
+    assert (
+        path_url.query_string
+        == "start=2022-03-27T14:05:00%2B03:00&end=2022-03-27T16:05:00%2B03:00"
+    )
+    assert path_url.query.get("start") == "2022-03-27T14:05:00+03:00"
+    assert path_url.query.get("end") == "2022-03-27T16:05:00+03:00"
+    new = original.join(path_url)
+    assert new.query.get("start") == "2022-03-27T14:05:00+03:00"
+    assert new.query.get("end") == "2022-03-27T16:05:00+03:00"
+
+
+def test_join_encoded_url():
+    """Test that url encoded urls are correctly joined."""
+    original = URL("http://127.0.0.1:62869")
+    path_url = URL("/api/%34")
+    assert original.path == "/"
+    assert path_url.path == "/api/4"
+    new = original.join(path_url)
+    assert new.path == "/api/4"