Merge branch 'ds/sparse-cone' into maint

Merge branch 'ds/sparse-cone' into maint

The code recently added in this release to move to the entry beyond
the ones in the same directory in the index in the sparse-cone mode
did not count the number of entries to skip over incorrectly, which
has been corrected.

* ds/sparse-cone:
  .mailmap: fix GGG authoship screwup
  unpack-trees: correctly compute result count