supporting google_cloud_core[grpc] style package names

[asa]

Trying to pip package google-cloud-logging, which depends on the strangely named google_cloud_core[grpc] package causes problems.
if my py_image target has a layer thats looking for requirement("google-cloud-logging"), I get the following:

ubuntu@ubuntu-xenial:/code$ bazel build app:app_image
ERROR: /home/ubuntu/.cache/bazel/_bazel_ubuntu/3a20ab50938efa4ee22db80044ad3a50/external/pypi__google_cloud_logging_1_4_0/BUILD:6:1: Traceback (most recent call last):
File "/home/ubuntu/.cache/bazel/_bazel_ubuntu/3a20ab50938efa4ee22db80044ad3a50/external/pypi__google_cloud_logging_1_4_0/BUILD", line 6
py_library(name = "pkg", srcs = glob(["**/*.p..."]), <3 more arguments>)
File "/home/ubuntu/.cache/bazel/_bazel_ubuntu/3a20ab50938efa4ee22db80044ad3a50/external/pypi__google_cloud_logging_1_4_0/BUILD", line 13, in py_library
requirement("google-cloud-core[grpc]")
File "/home/ubuntu/.cache/bazel/_bazel_ubuntu/3a20ab50938efa4ee22db80044ad3a50/external/gcloud_minimal/requirements.bzl", line 290, in requirement
_requirements[name]
key "google_cloud_core[grpc]" not found in dictionary
ERROR: /code/app/BUILD:37:1: no such target '@pypi__google_cloud_logging_1_4_0//:pkg': target 'pkg' not declared in package '' defined by /home/ubuntu/.cache/bazel/_bazel_ubuntu/3a20ab50938efa4ee22db80044ad3a50/external/pypi__google_cloud_logging_1_4_0/BUILD and referenced by '//app:app_image.binary'

Many other pip packages install fine this way, just not the google cloud ones that end up looking for grpc this way, such as googleapis-common-protos[grpc]

Any help would be great.

[mattmoor]

Does this reproduce against the latest version of rules_python? I expect it should be covered by the support for "extras" which landed relatively recently.

[asa]

Ha! yes, what a difference a few days makes. This works fine in 44711d8 Thanks!