zstd tests fail with libzstd 1.3.0

When I run the unit tests on tor master: [notice] Tor 0.3.2.0-alpha-dev (git-9a1338d9df938fba) running on Darwin with Libevent 2.1.8-stable, OpenSSL 1.0.2l, Zlib 1.2.11, Liblzma 5.2.3, and Libzstd 1.3.0.

I see the following failures:

buffer/compress/zstd: [forking] 
  FAIL src/test/test_buffers.c:607: assert(write_to_buf_compress(buf, compress_state, "", 0, 1) OP_EQ 0): -1 vs 0
  FAIL src/test/test_buffers.c:607: assert(write_to_buf_compress(buf, compress_state, "", 0, 1) OP_EQ 0): -1 vs 0
  FAIL src/test/test_buffers.c:607: assert(write_to_buf_compress(buf, compress_state, "", 0, 1) OP_EQ 0): -1 vs 0
  FAIL src/test/test_buffers.c:607: assert(write_to_buf_compress(buf, compress_state, "", 0, 1) OP_EQ 0): -1 vs 0
  [compress/zstd FAILED]
...
util/compress_concat/zstd: 
  FAIL src/test/test_util.c:2414: assert(r OP_EQ 0): -1 vs 0
  [compress_concat/zstd FAILED]