fix: Find first source package name for a binary package with publish…

…ed sources

If a changelog is not found for a binary package then iterate through list of all source package
for with binaries published of that name - not just the first source package found.

This fixes a problem with metapackages like linux-gce-edge:

```
❯ ubuntu-package-changelog --entries=1 jammy Updates linux-gcp-edge
no changelog found
```

vs (with the commit present)

```
❯ ubuntu-package-changelog --entries=1 jammy Updates linux-gcp-edge
INFO: No published sources found for linux-gcp-edge in jammy Updates
INFO:   Trying to find a binary package with that name ...
INFO:   Found source package linux-meta-gcp-6.2 for binary package linux-gcp-edge with published sources.
INFO:   Changelog for source package linux-meta-gcp-6.2 will be parsed

linux-meta-gcp-6.2 (6.2.0.1010.10~22.04.1) jammy; urgency=medium

  * Bump ABI 6.2.0-1010.10~22.04

  * Packaging resync (LP: #1786013)
    - [Packaging] resync debian/dkms-versions from main package

 -- Khalid Elmously <[email protected]>  Tue, 18 Jul 2023 04:39:30 -0400

```

The source packages are sorted by date with newest first so we will always have the latest returned.

In this instance it is a metadata package which will not have a very informative changleog but it
is more helpful than no changelog and at least it is known what the source package name is.

ubuntu_package_changelog/__init__.py

@@ -24,6 +24,8 @@ def _lp_get_changelog_url(args, lp):
                                      lp_series,
                                      pocket)
     if len(sources) == 0:
+        print(f'INFO: No published sources found for {args.package} in {args.series} {args.pocket}')
+        print('INFO: \tTrying to find a binary package with that name ...')
         # unable to find published sources for args.package.
         # Perhaps this is a binary package name so we can
         # do a lookup to see if there exists a source package for
@@ -34,11 +36,19 @@ def _lp_get_changelog_url(args, lp):
         if len(binaries):
             # there were published binaries with this name.
             # now get the source package name so we can get the changelog
-            source_package_name = binaries[0].source_package_name
-            sources = _get_published_sources(archive,
-                                             source_package_name,
-                                             lp_series,
-                                             pocket)
+            for binary in binaries:
+                source_package_name = binary.source_package_name
+                sources = _get_published_sources(archive,
+                                                 source_package_name,
+                                                 lp_series,
+                                                 pocket)
+                if len(sources) > 0:
+                    print(f'INFO: \tFound source package {source_package_name} for binary package '
+                          f'{args.package} with published sources.')
+                    print(f'INFO: \tChangelog for source package {source_package_name} will be parsed\n\n')
+                    break
+        else:
+            print(f'INFO: \tNo published binaries found for {args.package} in {args.series} {args.pocket}\n\n')
 
     if len(sources) == 1:
         return sources[0].changelogUrl()
@@ -106,7 +116,8 @@ def main():
 
     changelog_url = _lp_get_changelog_url(args, lp)
     if not changelog_url:
-        print('no changelog found')
+        print('No changelog found for binary or source package "{}" in {} {}'.format(
+            args.package, args.series, args.pocket))
         sys.exit(0)
 
     url = lp._root_uri.append(urllib.parse.urlparse(changelog_url).path.lstrip('/'))