Summary:
To correct a build process where the JAVA_TEST_LIBDIR is a symlink to a cache directory.
Test -s (size 0) on symlinks returns true, resulting in a mkdir over the top of the symlink resulting in failure.
As a solution -d checks if it is a directory (or the symlink refers to a directory), which works in the case of real directories and symlinks to directories.
Trivial I know but it was really easy for me to use a symlink here to prevent frequent downloads in a CI environment.
Thanks for your consideration.
Closes https://github.com/facebook/rocksdb/pull/1917
Differential Revision: D4612263
Pulled By: siying
fbshipit-source-id: 4d458f8e1760068cdd6b5eae4bce6e12c400df41
3eab41d7c4