Josh Steadmon [off-list ref] writes:

Unfortunately, it seems this patch breaks the subtree tests. We noticed
a failure in our build system at $WORK, and I was able to bisect the
failure to this commit:

$ git bisect start 54b18a3513eed9ed5ced5c238ade55a434fd619a 66b2238f5c17644ddf15f75a53c76faeca6d9f1e
$ git bisect run sh -c 'make && make -C contrib/subtree && make -C contrib/subtree test'

The tests fail on case 17 - split requires path given by option --prefix
must exist.

Thanks for a quick regression report while it is still in 'next', so
that we can revert it out of 'next' without breaking the 'master'.