package_manager.py: Avoid installing an empty package list

It is possible in an attempt only install, that everything listed is not
available to be installed.  This will have the effect of clearing the
package list.  However, we only check for an empty package list at
the beginning of the function.  We need to also check before running the
install, otherwise we can fail due to 'error: no package(s) given".

(From OE-Core rev: 9ae6a2830dacb3c335754a6da91bd5cc30546b31)

Signed-off-by: Mark Hatle <mark.hatle@windriver.com>
Signed-off-by: Mingli Yu <mingli.yu@windriver.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/lib/oe/package_manager.py

@@ -1186,6 +1186,9 @@ class RpmPM(PackageManager):
                     new_depends[new_depend] = deps[depend]
                 pkgs = bb.utils.join_deps(new_depends, commasep=True).split(', ')
         pkgs = self._pkg_translate_oe_to_smart(pkgs, attempt_only)
+        if not pkgs:
+            bb.note("There are no packages to install")
+            return
         if not attempt_only:
             bb.note('to be installed: %s' % ' '.join(pkgs))
             cmd = "%s %s install -y %s" % \