Fix issue #1022: version_keyword should override infer_version when config differs

When infer_version sets a version first, version_keyword should be able to
override it if it brings additional configuration (like a different version_scheme).

This commit implements a marker system:
- infer_version sets _setuptools_scm_version_set_by_infer=True when it sets a version
- version_keyword checks this marker and:
  - If no overrides: uses infer_version result (no warning)
  - If overrides present: clears version and recalculates with new config
  - If version set by other means: warns as before

This allows proper integration behavior where version_keyword can override
infer_version when the user provides specific configuration like calver schemes.

Author: RonnyPfannschmidt

CHANGELOG.md

@@ -11,6 +11,7 @@
 - add `scm` parameter support to `get_version()` function for nested SCM configuration
 - fix #987: expand documentation on git archival files and add cli tools for good defaults
 - fix #311: document github/gitlab ci pipelines that enable auto-upload to test-pypi/pypi
+- fix #1022: allow `version_keyword` to override `infer_version` when configuration differs
 
 
 ### Changed

src/setuptools_scm/_integration/setuptools.py

@@ -108,8 +108,21 @@ def version_keyword(
     _log_hookstart("version_keyword", dist)
 
     if dist.metadata.version is not None:
-        warnings.warn(f"version of {dist_name} already set")
-        return
+        # Check if version was set by infer_version
+        was_set_by_infer = getattr(dist, "_setuptools_scm_version_set_by_infer", False)
+
+        if was_set_by_infer:
+            # Version was set by infer_version, check if we have overrides
+            if not overrides:
+                # No overrides, just use the infer_version result
+                return
+            # We have overrides, clear the marker and proceed to override the version
+            dist._setuptools_scm_version_set_by_infer = False  # type: ignore[attr-defined]
+            dist.metadata.version = None
+        else:
+            # Version was set by something else, warn and return
+            warnings.warn(f"version of {dist_name} already set")
+            return
 
     if dist_name is None:
         dist_name = read_dist_name_from_setup_cfg()
@@ -141,3 +154,5 @@ def infer_version(dist: setuptools.Distribution) -> None:
         log.info(e, exc_info=True)
     else:
         _assign_version(dist, config)
+        # Mark that this version was set by infer_version
+        dist._setuptools_scm_version_set_by_infer = True  # type: ignore[attr-defined]