MINOR: [Archery] Improve crossbow report-pr ergonomics (#13994)

* If a pull request with the given title is not found, also print the repo name.
* Allow shorthand "username/reponame" as remote, in addition to full Github URLs.

Authored-by: Antoine Pitrou <antoine@python.org>
Signed-off-by: Antoine Pitrou <antoine@python.org>

dev/archery/archery/crossbow/cli.py

@@ -304,8 +304,8 @@ def asset_callback(task_name, task, asset):
 @click.option('--arrow-remote', '-r', default=None,
               help='Set GitHub remote explicitly, which is going to be cloned '
                    'on the CI services. Note, that no validation happens '
-                   'locally. Examples: https://github.com/apache/arrow or '
-                   'https://github.com/raulcd/arrow.')
+                   'locally. Examples: "https://github.com/apache/arrow" or '
+                   '"raulcd/arrow".')
 @click.option('--crossbow', '-c', default='ursacomputing/crossbow',
               help='Crossbow repository on github to use')
 @click.option('--fetch/--no-fetch', default=True,

dev/archery/archery/crossbow/core.py

@@ -211,10 +211,13 @@ def _git_ssh_to_https(url):
 def _parse_github_user_repo(remote_url):
     m = re.match(r'.*\/([^\/]+)\/([^\/\.]+)(\.git)?$', remote_url)
     if m is None:
-        raise CrossbowError(
-            "Unable to parse the github owner and repository from the "
-            "repository's remote url '{}'".format(remote_url)
-        )
+        # Perhaps it's simply "username/reponame"?
+        m = re.match(r'^(\w+)/(\w+)$', remote_url)
+        if m is None:
+            raise CrossbowError(
+                f"Unable to parse the github owner and repository from the "
+                f"repository's remote url {remote_url!r}"
+            )
     user, repo = m.group(1), m.group(2)
     return user, repo
 
@@ -557,7 +560,8 @@ def github_pr(self, title, head=None, base="master", body=None,
                 if title in pull.title:
                     return pull
             raise CrossbowError(
-                f"Pull request with Title: {title} not found"
+                f"Pull request with Title: {title!r} not found "
+                f"in repository {repo.full_name!r}"
             )