Fill out lsb_distrib_xxx grains (best guess) if lsb_release information unavailable

changelog/64473.fixed.md

@@ -0,0 +1 @@
+Fill out lsb_distrib_xxxx (best estimate) grains if problems with retrieving lsb_release data

salt/grains/core.py

@@ -2175,8 +2175,9 @@ def _linux_distribution_data():
             "rocky",
             "ubuntu",
         ):
-            # Solely use os-release data. See description of the function.
-            return grains
+            if lsb_has_error is False:
+                # Solely use os-release data. See description of the function.
+                return grains
 
     except OSError:
         os_release = {}

tests/pytests/functional/grains/test_grains.py

@@ -0,0 +1,26 @@
+import logging
+
+import pytest
+
+log = logging.getLogger(__name__)
+
+
+pytestmark = [
+    pytest.mark.skip_unless_on_linux,
+    pytest.mark.skipif(
+        'grains["os_family"] != "Debian"',
+        reason="Tests applicable only to Debian and Ubuntu",
+    ),
+]
+
+
+def test_grains(grains):
+    log.warning(f"DGM test_grains '{grains}'")
+
+    assert "lsb_distrib_id" in grains
+    assert "lsb_distrib_release" in grains
+    assert "lsb_distrib_codename" in grains
+
+    assert grains["lsb_distrib_id"] == grains["osfullname"]
+    assert grains["lsb_distrib_release"] == grains["osrelease"]
+    assert grains["lsb_distrib_codename"] == grains["oscodename"]