[OE-core] [PATCH v2] python*-setuptools: add separate packages for pkg_resources module

[luca.boccassi at gmail.com]

From: Luca Boccassi <luca.boccassi at microsoft.com>

The pkg_resources Python module is useful by itself, for example for
automatic loading of resources shipped in a Python package.
Add separate packages for it, so that users can depend on them
individually and avoid pulling in the entire setuptools, which
include scripts to download other packages, which might not be
desired on minimal images.

Other distributions like Debian and Ubuntu already split setuptools
and pkg-resources in this way.

The setuptools packages now depend on the new pkg-resources packages,
to avoid regressions for other packages that depend on them
already.

Signed-off-by: Luca Boccassi <luca.boccassi at microsoft.com>
---
v2: restrict new RDEPENDS to class-target. As advised by Alexander, bitbake
    cannot resolve native rdeps that mention package names rather than
    recipe names.

 meta/recipes-devtools/python/python-setuptools.inc | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/meta/recipes-devtools/python/python-setuptools.inc b/meta/recipes-devtools/python/python-setuptools.inc
index 357aa07086..c5dcee7059 100644
--- a/meta/recipes-devtools/python/python-setuptools.inc
+++ b/meta/recipes-devtools/python/python-setuptools.inc
@@ -37,3 +37,9 @@ do_install_prepend() {
 }
 
 BBCLASSEXTEND = "native nativesdk"
+
+PACKAGES =+ "${PYTHON_PN}-pkg-resources "
+FILES_${PYTHON_PN}-pkg-resources = "${PYTHON_SITEPACKAGES_DIR}/pkg_resources/*"
+# Due to a bitbake bug, the native class cannot have a dependency on something
+# that is not a recipe name.
+RDEPENDS_${PN}_append_class-target = " ${PYTHON_PN}-pkg-resources"
-- 
2.20.1