Allow for more control in template variables

Sepearate commit message coming from git for handling in template.

tests/prepare_commit_msg_test.py

@@ -52,13 +52,13 @@ TESTS = (
     ),
     (
         b'',
-        b'\n\nRelates: AA-01',
+        b'\n\nRelates: #AA-01\n\n',
         'feature/AA-01',
         get_template_path('prepare_commit_msg_append.j2'),
     ),
     (
         b'Initial message',
-        b'Initial message\n\nRelates: AA-02',
+        b'Initial message\n\nRelates: #AA-02\n\n',
         'feature/AA-02',
         get_template_path('prepare_commit_msg_append.j2'),
     ),
@@ -110,3 +110,44 @@ def test_main(
             ],
         ) == 0
         assert path.read_binary() == expected_val
+
+
+TESTS_TEMPLATES = (
+    (
+        b'Initial Message\n\n# Git commented\n# output simulated',
+        b'[1.0.0] Initial Message\n\n# Git commented\n# output simulated',
+        'release/1.0.0',  # but this should
+        get_template_path('prepare_commit_msg_prepend.j2'),
+    ),
+    (
+        b'Initial Message\n# Git commented\n# output simulated',
+        b'Initial Message\n\nRelates: #1.0.0\n\n'
+        b'# Git commented\n# output simulated',
+        'release/1.0.0',  # but this should
+        get_template_path('prepare_commit_msg_append.j2'),
+    ),
+)
+
+
+@pytest.mark.parametrize(
+    ('input_s', 'expected_val', 'branch_name', 'template'),
+    TESTS_TEMPLATES,
+)
+def test_main_separating_content(
+        input_s, expected_val, branch_name, template,
+        temp_git_dir,
+):
+    with temp_git_dir.as_cwd():
+        path = temp_git_dir.join('file.txt')
+        path.write_binary(input_s)
+        assert path.read_binary() == input_s
+
+        cmd_output('git', 'checkout', '-b', branch_name)
+        assert main(
+            argv=[
+                '-t', template,
+                '-p', '(?<=release/).*',
+                str(path),
+            ],
+        ) == 0
+        assert path.read_binary() == expected_val