Change cpack generated name for component RPMs

This is a copy of a question I've added on stack overflow (https://stackoverflow.com/questions/45332445/change-cpack-generated-name-for-component-rpms) which I think may indicate a bug. At the very least the documentation (https://cmake.org/Wiki/CMake:Component_Install_With_CPack) is insufficiently helpful.

I am trying to create an RPM installer using cpack (via cmake) that creates multiple RPM files. I've almost got it working but the last remaining stumbling block is controlling the package names. Specifically I want to control where the component name appears in the RPM file name.

Here is my experimental CMakeLists.txt file which installs foo.txt and bar.txt to two different packages "myproject-foo" & "myproject-bar". I want the RPMs to follow my own naming conventions (actually I want conventions that are more FSH friendly) but for some reason cmake insists on adding the component name at the end. So I get:

myproject-comp-1.0.i686-foo.rpm
myproject-comp-1.0.i686-bar.rpm

rather than:

myproject-compfoo-1.0.i686.rpm
myproject-compbar-1.0.i686.rpm

I notice it names the source RPMs "more correctly": E.g.

>rpm -qip <package> | grep source
Source RPM  : myproject-foo-1.0-1.src.rpm

Though I do not actually want a source RPM at all (is there a way to blank this field?)

cmake_minimum_required(VERSION 2.8)

message("CMAKE_VERSION=${CMAKE_VERSION}")

SET(DOCDIR "doc")
set(CMAKE_INSTALL_DEFAULT_COMPONENT_NAME "core")
install(FILES foo.txt COMPONENT foo DESTINATION "${RPMBUILDROOT}${DOCDIR}")
install(FILES bar.txt COMPONENT bar DESTINATION "${RPMBUILDROOT}${DOCDIR}")

project(myproject CXX)

set(CPACK_PACKAGE_NAME "myproject")
set(CPACK_RPM_COMPONENT_INSTALL ON)
set(CPACK_PACKAGE_VERSION 1.0)
set(CPACK_PACKAGE_VENDOR "some org")

set(CPACK_COMPONENT_foo_DESCRIPTION "the foo component")
set(CPACK_COMPONENT_bar_DESCRIPTION "the bar component")

# mentioned in cpack docs but doesn't seem to do anything here
set(CPACK_COMPONENT_foo_DISPLAY_NAME "foo display name?")
set(CPACK_COMPONENT_bar_DISPLAY_NAME "foo display name?")

set(CPACK_COMPONENT_bar_DEPENDS foo)

set(CPACK_PACKAGE_DESCRIPTION_SUMMARY "describe the complete suite of stuff")
set(CPACK_PACKAGE_DESCRIPTION_FILE ${CMAKE_SOURCE_DIR}/README.txt)

# added in cmake 3.6?
set(CPACK_RPM_foo_PACKAGE_SUMMARY "describe the foo package")
set(CPACK_RPM_bar_PACKAGE_SUMMARY "describe the bar package")
set(CPACK_RPM_foo_PACKAGE_NAME "${CPACK_PACKAGE_NAME}-foo")
set(CPACK_RPM_bar_PACKAGE_NAME "${CPACK_PACKAGE_NAME}-bar")

set(CPACK_PACKAGE_DESCRIPTION_FILE ${CMAKE_SOURCE_DIR}/README.txt)

#set(CPACK_RPM_foo_PACKAGE_FILE_NAME "${CPACK_PACKAGE_NAME}-foo-${CPACK_PACKAGE_VERSION}.i686")
#set(CPACK_RPM_bar_PACKAGE_FILE_NAME "${CPACK_PACKAGE_NAME}-bar-${CPACK_PACKAGE_VERSION}.i686")


set(CPACK_PACKAGING_INSTALL_PREFIX ${CMAKE_INSTALL_PREFIX})
set(CPACK_PACKAGE_FILE_NAME "${CPACK_PACKAGE_NAME}-comp${CPACK_COMPONENT_DISPLAY_NAME}-${CPACK_PACKAGE_VERSION}.i686")

set(CPACK_RPM_PACKAGE_ARCHITECTURE "i686")
set(CPACK_RPM_PACKAGE_RELOCATABLE TRUE)

include(CPack)

cpack_add_component(foo
                    DISPLAY_NAME foo comp
                    DESCRIPTION this is the foocomp)
cpack_add_component(bar
                    DISPLAY_NAME bar comp
                    DESCRIPTION this is the bar comp
		    DEPENDS foo)

It seems like CPACK_PACKAGE_<component>_FILE_NAME or CPACK_PACKAGE_FILE_NAME is not quite working. I've tried with both cmake 3.4.3 and the latest (3.9.0 at the time of writing) as there is some suggestion of fixes to component based installs in 3.6.0

There is no such variable as the CPACK_COMPONENT_DISPLAY_NAME I've used in CPACK_PACKAGE_FILE_NAME. Also something in cmake adds the component name to the end automatically.

There is a similar question for .deb packages from long ago here but I would rather avoid such a complex solution if possible. It would be easier to rename the packages after generation (but still feel hacky).

I also note that the package dependency set(CPACK_COMPONENT_bar_DEPENDS foo) is not recorded in the bar package.