Release prep for version 0.3.4.

Also apply suggestions from code review

Co-authored-by: Ben Jeffery <ben.jeffery@gmail.com>

Author: jeromekelleher

python/CHANGELOG.rst

@@ -1,13 +1,14 @@
 --------------------
-[0.X.X] - 2021-XX-XX
+[0.3.4] - 2020-12-02
 --------------------
 
-**Breaking changes**
+Minor bugfix release.
 
-**Features**
 
 **Bugfixes**
 
+- Reinstate the unused zlib_compression option to tskit.dump, as msprime < 1.0
+  still uses it (:user:`jeromekelleher`, :issue:`1067`).
 
 --------------------
 [0.3.3] - 2020-11-27

python/tests/test_highlevel.py

@@ -1288,16 +1288,15 @@ def test_dump_load_errors(self):
                 with pytest.raises(TypeError):
                     func(bad_filename)
 
-    def test_zlib_compression_warning(self, ts_fixture):
-        with tempfile.TemporaryDirectory() as tempdir:
-            temp_file = pathlib.Path(tempdir) / "tmp.trees"
-            with warnings.catch_warnings(record=True) as w:
-                ts_fixture.dump(temp_file, zlib_compression=True)
-                assert len(w) == 1
-                assert issubclass(w[0].category, RuntimeWarning)
-            with warnings.catch_warnings(record=True) as w:
-                ts_fixture.dump(temp_file, zlib_compression=False)
-                assert len(w) == 0
+    def test_zlib_compression_warning(self, ts_fixture, tmp_path):
+        temp_file = tmp_path / "tmp.trees"
+        with warnings.catch_warnings(record=True) as w:
+            ts_fixture.dump(temp_file, zlib_compression=True)
+            assert len(w) == 1
+            assert issubclass(w[0].category, RuntimeWarning)
+        with warnings.catch_warnings(record=True) as w:
+            ts_fixture.dump(temp_file, zlib_compression=False)
+            assert len(w) == 0
 
     def test_tables_sequence_length_round_trip(self):
         for sequence_length in [0.1, 1, 10, 100]:

python/tskit/_version.py

@@ -1,4 +1,4 @@
 # Definitive location for the version number.
 # During development, should be x.y.z.devN
 # For beta should be x.y.zbN
-tskit_version = "0.3.4.dev1"
+tskit_version = "0.3.4"