Table and partition statistics are Puffin files that the table metadata lists
in its statistics entries; orphan cleanup keeps them (#11651), and its test
places one at metadata/stats-1.puffin. The table bucket layout rule accepted
only *.stats among them, so an engine that names a statistics file *.puffin
had the upload refused with 403 and could not write statistics at all.
The metadata patterns now admit a *.puffin file directly under metadata/,
with the same safe-character rule as the other catch-all patterns. Nothing
else widens: a Puffin file in a subdirectory of metadata/, with a trailing
extension, or outside <namespace>/<table>/ is still refused.
Test: the new metadata/*.puffin cases in
TestIcebergLayoutValidator_AcceptsRealWorldManifestNames and
TestTableBucketFileValidator_PuffinStatisticsOnlyInTableMetadata fail on
master ("invalid metadata file format") and pass with the change; the
rejected cases pass on both.
Co-authored-by: Javier de la Torre <jatorre@lakehousebox.com>