040000 tree 51af88f7294af98930957bb9ae3004aa8ef36359	bazel_0.16.1
040000 tree 97423f10479f6a655d4cdd92374747c1b41146e4	bazel_0.17.1
040000 tree 2d479c14c8a826666719f453bba94e81edd843a5	bazel_0.18.0
040000 tree e83f0baa3f5ec5c35b62cfe74262577ffaddbc1c	bazel_0.19.0