Vendoring is broken

[bendavini]

🐞 bug report

Affected Rule

vendored pip_parse dependencies

Is this a regression?

Yes, fixed in #608 and linked issues

Description

Clients of a vendored workspace (e.g., pip_parse_vendored) cannot use the 1-step solution documented in the readme and are instead still required to pip_parse their dependency's dependencies.

🔬 Minimal Reproduction

From slack thread (as of 66550eca4ae9d94be3a32da86e60a54cba13cf74):
Create a directory in use_pip_parse_vendored in rules_python/examples
WORKSPACE:

workspace(name = "use_pip_parse_vendored")

local_repository(
    name = "rules_python",
    path = "../..",
)

local_repository(
    name = "pip_parse_vendored",
    path = "../pip_parse_vendored",
)

load("@rules_python//python:repositories.bzl", "py_repositories", "python_register_toolchains")

py_repositories()

python_register_toolchains(
    name = "python39",
    python_version = "3.9",
)

load("@pip_parse_vendored//:requirements.bzl", "install_deps")

install_deps()

hello_world.py in same directory (that wants to use one of the pip_parse_vendored requirements):

#!/usr/bin/env python3
import urllib3
if __name__ == "__main__":
    print("Hello world")
    http = urllib3.PoolManager()
    resp = http.request("GET", "https://httpbin.org/robots.txt")
    print(resp.data)

BUILD.bazel file that uses the dependency:

load("@rules_python//python:defs.bzl", "py_binary")
load("@pip_parse_vendored//:requirements.bzl", "requirement")

py_binary(
    name = "hello_world",
    srcs = ["hello_world.py"],
    visibility = ["//:__subpackages__"],
    deps = [
        requirement("urllib3"),
    ]
)

🔥 Exception or Error

Bazel 7.1.2:

bazel build ...
ERROR: no such package '@@[unknown repo 'pip' requested from @@]//urllib3': The repository '@@[unknown repo 'pip' requested from @@]' could not be resolved: No repository visible as '@pip' from main repository
ERROR: /Users/davinib/code/git/nonvmware/bazel/rules_python/examples/use_pip_parse_vendored/BUILD.bazel:4:10: no such package '@@[unknown repo 'pip' requested from @@]//urllib3': The repository '@@[unknown repo 'pip' requested from @@]' could not be resolved: No repository visible as '@pip' from main repository and referenced by '//:hello_world'
ERROR: Analysis of target '//:hello_world' failed; build aborted: Analysis failed
INFO: Elapsed time: 0.946s, Critical Path: 0.01s
INFO: 1 process: 1 internal.
ERROR: Build did NOT complete successfully

Bazel 6.4.0:

ERROR: /Users/davinib/code/git/nonvmware/bazel/rules_python/examples/use_pip_parse_vendored/BUILD.bazel:4:10: no such package '@pip//urllib3': The repository '@pip' could not be resolved: Repository '@pip' is not defined and referenced by '//:hello_world'
ERROR: Analysis of target '//:hello_world' failed; build aborted: Analysis failed

🌍 Your Environment

Mac x86 14.4.1 (23E224)

Output of bazel version:
Both 7.1.2 and 6.4.0

Rules_python version:
ToT on 0.32.2 - 66550eca4ae9d94be3a32da86e60a54cba13cf74

Anything else relevant?
From slack thread:
Yeah, it is unfortunate that it is broken right now and the reason is that we are using aliases in the requirements.bzl for accessing the packages.
I think the targets in https://github.com/bazelbuild/rules_python/blob/main/examples/pip_parse_vendored/requirements.bzl#L9 should look like @pip_certify//:pkg instead of @pip//certify:pkg. Feel free to raise an issue in rules_python and a PR to fix this would be really welcome.
In the mean time the vendoring script could use some shell substitution like: sed 's|\(@pip\)//\(.*\):|\1_\2//:|g in order to get it generate the correct requirements.bzl.