gather: Skip lookaside packages from local lookaside repo

When variant X depends on variant A, Pungi creates a temporary local
lookaside with packages from A. If there's an external lookaside
configured, the list of package for variant A can contain URLs to the
external repo.

Newer versions of createrepo fail when pkglist specifies an unreachable
package, and it doesn't do downloading.

JIRA: RHELCMP-13648
Signed-off-by: Lubomír Sedlář <lsedlar@redhat.com>
(cherry picked from commit 4a5106375e)

pungi/phases/gather/__init__.py

@@ -666,6 +666,11 @@ def _make_lookaside_repo(compose, variant, arch, pkg_map, package_sets=None):
                 # we need a union of all SRPMs.
                 if pkg_type == "srpm" or pkg_arch == arch:
                     for pkg in packages:
+                        if "lookaside" in pkg.get("flags", []):
+                            # We want to ignore lookaside packages, those will
+                            # be visible to the depending variants from the
+                            # lookaside repo directly.
+                            continue
                         pkg = pkg["path"]
                         if path_prefix and pkg.startswith(path_prefix):
                             pkg = pkg[len(path_prefix) :]