fix(config): gracefully fail when repo is in a detached HEAD state (#765

)

* fix(config): cleanly handle repository in detached HEAD state

* test(cli-main): add detached head cli test

semantic_release/cli/config.py

@@ -257,8 +257,18 @@ def from_raw_config(
         ##
         # credentials masking for logging
         masker = MaskingFilter(_use_named_masks=raw.logging_use_named_masks)
+
+        try:
+            active_branch = repo.active_branch.name
+        except TypeError as err:
+            raise NotAReleaseBranch(
+                "Detached HEAD state cannot match any release groups; "
+                "no release will be made"
+            ) from err
+
         # branch-specific configuration
-        branch_config = cls.select_branch_options(raw.branches, repo.active_branch.name)
+        branch_config = cls.select_branch_options(raw.branches, active_branch)
+
         # commit_parser
         commit_parser_cls = (
             _known_commit_parsers[raw.commit_parser]

tests/command_line/test_main.py

@@ -37,6 +37,20 @@ def test_not_a_release_branch_exit_code_with_strict(
     assert result.exit_code != 0
 
 
+def test_not_a_release_branch_detached_head_exit_code(
+    repo_with_git_flow_angular_commits, cli_runner
+):
+    expected_err_msg = "Detached HEAD state cannot match any release groups; no release will be made"
+
+    # cause repo to be in detached head state without file changes
+    repo_with_git_flow_angular_commits.git.checkout("HEAD", "--detach")
+    result = cli_runner.invoke(main, ["version", "--no-commit"])
+
+    # as non-strict, this will return success exit code
+    assert result.exit_code == 0
+    assert expected_err_msg in result.stderr
+
+
 @pytest.fixture
 def toml_file_with_no_configuration_for_psr(tmp_path):
     path = tmp_path / "config.toml"