Fix setuptools_scm version retrieval from detached HEAD

setup.py

@@ -3,24 +3,21 @@
 from setuptools import setup
 from setuptools_scm.version import get_local_dirty_tag
 
-RELEASE_BRANCH = "main"
-
 
 def version_scheme(version) -> str:
     """Get version component for the current commit.
 
     Used by setuptools_scm.
     """
-    if version.branch == RELEASE_BRANCH:
-        if version.distance == 0:
-            # If the current commit is on the release branch and has a GIT tag,
-            # use the tag as version:
-            return f"{version.tag}"
-        else:
-            # For untagged commits always add a distance like ".post3"
-            return f"{version.tag}.post{version.distance}"
+    if version.tag and version.distance == 0:
+        # If the current commit has a tag, use the tag as version, regardless of branch.
+        # Note: Github CI creates releases from detached HEAD, not from a particular branch.
+        return f"{version.tag}"
+    elif version.branch == "main" and version.tag and version.distance > 0:
+        # For untagged commits on the release branch always add a distance like ".post3"
+        return f"{version.tag}.post{version.distance}"
     else:
-        # For non-release branches, make the version as dev and distance:
+        # For non-release branches, mark the version as dev and distance:
         return f"{version.tag}.dev{version.distance}"
 
 
@@ -29,16 +26,14 @@ def local_scheme(version) -> str:
 
     Used by setuptools_scm.
     """
-    # If current version is dirty, always add dirty tag, regardless of branch.
+    # If current version is dirty, always add dirty suffix, regardless of branch.
     dirty_tag = get_local_dirty_tag(version) if version.dirty else ""
     if dirty_tag:
         return f"{dirty_tag}.{version.node}"
 
-    if version.branch == RELEASE_BRANCH:
-        if version.distance == 0:
-            # no local component for versions on the main release branch:
-            # will create simple versions like 4.1.0
-            return ""
+    if version.distance == 0:
+        # If the current commit has a tag, do not add a local component, regardless of branch.
+        return ""
     # For all other cases, always add the git reference (like "g7839952")
     return f"+{version.node}"