address review comments

Author: rickeylev

python/features.bzl

@@ -13,9 +13,11 @@
 # limitations under the License.
 """Allows detecting of rules_python features that aren't easily detected."""
 
+# This is a magic string expanded by `git archive`, as set by `.gitattributes`
+# See https://git-scm.com/docs/git-archive/2.29.0#Documentation/git-archive.txt-export-subst
 _VERSION_PRIVATE = "$Format:%(describe:tags=true)$"
 
 features = struct(
-    version = _VERSION_PRIVATE if '$Format' not in _VERSION_PRIVATE else ''
+    version = _VERSION_PRIVATE if "$Format" not in _VERSION_PRIVATE else "",
     precompile = True,
 )