useradd: Fix useradd do_populate_sysroot dependency bug

If a task is adde which has a dependency on the do_populate_sysroot task of
the recipe, it will cause it to be installed into the sysroot (similar to
do_addto_recipe_sysroot). This fails since the postinst script is an overlapping
file:

Exception: FileExistsError: [Errno 17] File exists:
'tmp/sysroots-components/all/useraddbadtask/usr/bin/postinst-useradd-useraddbadtask'
  ->
'tmp/work/all-poky-linux/useraddbadtask/1.0/recipe-sysroot/usr/bin/postinst-useradd-useraddbadtask'

The copy written out at do_prepare_recipe_sysroot time is just for debug so
rename it, meaning there are no longer overlapping files and the installation
can be successful, removing the error.

[YCOTO #14961]

With the bug fixed, enable the test.

(From OE-Core rev: 564339afb73fc52a66c1a08437587cad1c4d46e7)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/useradd.bbclass

@@ -154,7 +154,11 @@ python useradd_sysroot_sstate () {
         bb.build.exec_func("useradd_sysroot", d)
     elif task == "prepare_recipe_sysroot":
         # Used to update this recipe's own sysroot so the user/groups are available to do_install
-        scriptfile = d.expand("${RECIPE_SYSROOT}${bindir}/postinst-useradd-${PN}")
+
+        # If do_populate_sysroot is triggered and we write the file here, there would be an overlapping
+        # files. See usergrouptests.UserGroupTests.test_add_task_between_p_sysroot_and_package
+        scriptfile = d.expand("${RECIPE_SYSROOT}${bindir}/postinst-useradd-${PN}-recipedebug")
+
         bb.build.exec_func("useradd_sysroot", d)
     elif task == "populate_sysroot":
         # Used when installed in dependent task sysroots