Grail bazel toolchain changed/missing

[jjh42]

tensorflow_io no longer builds (from master) due to some change recently in upstream deps.

http_archive(
name = "com_grail_bazel_toolchain",
sha256 = "9e6065ded4b7453143e1586d6819729a63cd233114b72bf85ff3435367b02c90",
strip_prefix = "bazel-toolchain-edd07e96a2ecaa131af9234d6582875d980c0ac7",
urls = [
"https://storage.googleapis.com/mirror.tensorflow.org/github.com/grailbio/bazel-toolchain/archive/edd07e96a2ecaa131af9234d6582875d980c0ac7.tar.gz",
"https://github.com/grailbio/bazel-toolchain/archive/edd07e96a2ecaa131af9234d6582875d980c0ac7.tar.gz",
],
)

the version on google storage no longer exists (404) and the version on github has a different hash (sha256=4b7999c1fa2c3117bb21651e3c155b152e44ae67b2c311214883d4707dbe183f). Note this changed just happened in the last few days but seems to be persistent.

I have tried from multiple IPs etc same result.