fixup! Move 'blurb merge' to blurb._merge

Author: AA-Turner

tests/test_parser.py

@@ -3,7 +3,8 @@
 
 import pytest
 
-from blurb.blurb import Blurbs, pushd
+from blurb._versions import chdir
+from blurb.blurb import Blurbs
 
 
 class TestParserPasses:
@@ -19,7 +20,7 @@ def filename_test(self, filename):
             assert str(b) == expected
 
     def test_files(self):
-        with pushd(self.directory):
+        with chdir(self.directory):
             for filename in glob.glob("*"):
                 if filename.endswith(".res"):
                     assert os.path.exists(filename[:-4]), filename