Allow passing a base branch that doesn't have version info

cherry_picker/cherry_picker.py

@@ -165,7 +165,7 @@ def upstream(self):
     @property
     def sorted_branches(self):
         """Return the branches to cherry-pick to, sorted by version."""
-        return sorted(self.branches, reverse=True, key=version_from_branch)
+        return sorted(self.branches, key=version_sort_key)
 
     @property
     def username(self):
@@ -733,7 +733,7 @@ def get_base_branch(cherry_pick_branch):
 
     # Subject the parsed base_branch to the same tests as when we generated it
     # This throws a ValueError if the base_branch doesn't meet our requirements
-    version_from_branch(base_branch)
+    version_sort_key(base_branch)
 
     return base_branch
 
@@ -753,23 +753,21 @@ def validate_sha(sha):
         )
 
 
-def version_from_branch(branch):
+def version_sort_key(branch):
     """
-    return version information from a git branch name
+    return sort key based on version information from a git branch name
     """
     try:
-        return tuple(
-            map(
-                int,
-                re.match(r"^.*(?P<version>\d+(\.\d+)+).*$", branch)
-                .groupdict()["version"]
-                .split("."),
-            )
-        )
+        match = re.match(r"^.*(?P<version>\d+(\.\d+)+).*$", branch)
+        raw_version = match.groupdict()["version"].split(".")
     except AttributeError as attr_err:
-        raise ValueError(
-            f"Branch {branch} seems to not have a version in its name."
-        ) from attr_err
+        if not branch:
+            raise ValueError("Branch name is an empty string.") from attr_err
+        # Use '0' to sort regular branch names *after* version numbers
+        return (1, branch)
+    else:
+        # Use '0' to sort version numbers *before* regular branch names
+        return (0, *(-int(x) for x in raw_version))
 
 
 def get_current_branch():

cherry_picker/test_cherry_picker.py

@@ -152,7 +152,7 @@ def test_get_base_branch_which_has_dashes(subprocess_check_output):
     [
         "backport-22a594a",  # Not enough fields
         "prefix-22a594a-2.7",  # Not the prefix we were expecting
-        "backport-22a594a-base",  # No version info in the base branch
+        "backport-22a594a-",  # No base branch
     ],
 )
 @mock.patch("subprocess.check_output")
@@ -194,6 +194,10 @@ def test_get_author_info_from_short_sha(subprocess_check_output):
             ["stable-3.1", "lts-2.7", "3.10-other", "smth3.6else"],
             ["3.10-other", "smth3.6else", "stable-3.1", "lts-2.7"],
         ),
+        (
+            ["3.7", "3.10", "2.7", "foo", "stable", "branch"],
+            ["3.10", "3.7", "2.7", "branch", "foo", "stable"],
+        ),
     ],
 )
 @mock.patch("os.path.exists")
@@ -208,20 +212,13 @@ def test_sorted_branch(os_path_exists, config, input_branches, sorted_branches):
     assert cp.sorted_branches == sorted_branches
 
 
-@pytest.mark.parametrize(
-    "input_branches",
-    [
-        (["3.1", "2.7", "3.x10", "3.6", ""]),
-        (["stable-3.1", "lts-2.7", "3.10-other", "smth3.6else", "invalid"]),
-    ],
-)
 @mock.patch("os.path.exists")
-def test_invalid_branches(os_path_exists, config, input_branches):
+def test_invalid_branch_empty_string(os_path_exists, config):
     os_path_exists.return_value = True
     cp = CherryPicker(
         "origin",
         "22a594a0047d7706537ff2ac676cdc0f1dcb329c",
-        input_branches,
+        ["3.1", "2.7", "3.10", "3.6", ""],
         config=config,
     )
     with pytest.raises(ValueError):