pkg_rpm can't set package_file_name = ${package_name}.rpm

[ashi009]

When package_file_name = ${package_name}.rpm, the rule will fail:

ERROR: file 'test.rpm' is generated by these conflicting actions:
Label: //:rpm
RuleClass: pkg_rpm rule
JavaActionClass: class com.google.devtools.build.lib.analysis.actions.StarlarkAction, class com.google.devtools.build.lib.analysis.actions.SymlinkAction
Configuration: 211cf97c47c3c3c62956d4ca62222b55a5848ae6122e5c02c157c85559f94b7f
Mnemonic: MakeRpm, Symlink
Action key: e01d1825161e914df618d1befd116e60fa70bc978a57f884fe40324b1bee6e03, 7a39b61d5744a8903119e17b3ddc7e56e330f240d2bead98c3ba081a81b5c9ac
Progress message: MakeRpm test.rpm, Creating symlink bazel-out/aarch64-fastbuild/bin/test.rpm
Action describeKey: MakeRpm test.rpm
...

relevant callsites:

rules_pkg/pkg/rpm_pfg.bzl

Lines 492 to 497 in 12fed4b

	if ctx.attr.package_name:
	rpm_name = ctx.attr.package_name
	else:
	rpm_name = ctx.attr.name
	default_file = ctx.actions.declare_file("{}.rpm".format(rpm_name))

rules_pkg/pkg/rpm_pfg.bzl

Lines 701 to 705 in 12fed4b

	_, output_file, _ = setup_output_files(
	ctx,
	package_file_name = package_file_name,
	default_output_file = default_file,
	)

So the default_file is {rpm_name}.rpm where rpm_name is package_name, and output_file generates a file {package_file_name}, and it will cause the conflict.