fix: find the branch in a URL into a folder

A /tree/<branch>/<dir> URL was read as one branch name, so the
repository never resolved. Each prefix is tried, shortest first.
A repository that answers nothing now says so, or reports the
declared upstream_gone.

emulators/pyxel.yml

@@ -5,6 +5,7 @@ source: "https://github.com/kitao/pyxel"
 upstream: "https://github.com/kitao/pyxel"
 profiled_date: "2026-10-04"
 source_commit: "50f9bd77780c993aca62b5b221766bde5791081d"
+upstream_gone: "github.com/kitao/pyxel answers HTTP 404 to the API and the web, with no redirect. Observed 2026-10-18; no mirror found."
 core_version: "v2.9.9"
 display_name: "Pyxel"
 cores: [pyxel]

scripts/profile_sync.py

@@ -1293,15 +1293,19 @@ def select_views(
         # no profile carries, and fell back to profiled_date, which a bump
         # never moves (eden judged from f6e76860 while pinned on d16735f5).
         pin_field = "source" if field == "source_mirror" else field
-        branch = branch_in_url(url) or (
-            declared if pin_field == "source" else None
-        )
+        branch = declared if pin_field == "source" else None
+        head = None
+        for candidate in branch_candidates(url):
+            head = upstream.resolve_head(repo, cache_dir, offline, candidate)
+            if head:
+                branch = candidate
+                break
         pin, origin = resolve_pin(
             profile, repo, cache_dir, offline, pin_field, mode, branch
         )
         if not pin:
             continue
-        head = upstream.resolve_head(repo, cache_dir, offline, branch)
+        head = head or upstream.resolve_head(repo, cache_dir, offline, branch)
         if not head:
             continue
         seen.add((repo.host, repo.slug))
@@ -1372,12 +1376,29 @@ def branch_in_url(url: str) -> str | None:
     """Branch named by a forge URL pointing inside a repository.
 
     A profile can cite a fork as `.../Ymir/tree/libretro`, which names both
-    the repository and the branch the port lives on.
+    the repository and the branch the port lives on. The tail may go on into
+    a directory (`.../libretro-samples/tree/master/tests/cruzes`): this is
+    the whole tail, and branch_candidates() its prefixes.
     """
     _, sep, tail = url.partition("/tree/")
     return tail.strip("/") or None if sep else None
 
 
+def branch_candidates(url: str) -> list[str]:
+    """Each prefix of a /tree/ tail, shortest first, that may be the branch.
+
+    A branch name can hold a slash, so the tail is not split blindly; the
+    first prefix the forge resolves is the branch, the rest a directory.
+    Taken whole, `master/tests/cruzes` resolved to nothing and the profile
+    was skipped as having no resolvable pin.
+    """
+    tail = branch_in_url(url)
+    if not tail:
+        return []
+    parts = tail.split("/")
+    return ["/".join(parts[:n]) for n in range(1, len(parts) + 1)]
+
+
 SELF_CHECK_CONTEXT = 2
 
 
@@ -1632,9 +1653,18 @@ def build_report(
             f"upstream_gone is declared but the forge answers: {stated_gone}"
         )
         return report
+    if not views and stated_gone:
+        report.skipped = f"upstream gone (declared): {stated_gone}"
+        return report
     if not views:
+        # A declared pin whose repository or branch does not answer is not a
+        # profile without a pin: pyxel's kitao/pyxel answers 404, and the
+        # message sent the reader looking for a missing source_commit.
         report.skipped = (
-            "no source_commit and no resolvable profiled_date "
+            "no declared repository answers (moved, removed, or a branch the "
+            "forge does not know)"
+            if profile.get("source_commit") or profile.get("upstream_commit")
+            else "no source_commit and no resolvable profiled_date "
             "on any declared repository"
         )
         return report

tests/test_profile_sync.py

@@ -4070,5 +4070,60 @@ class TestSelectionNamesWhatMatchedNothing(unittest.TestCase):
         self.assertEqual(sorted(selected), ["handy", "mednafen_lynx"])
 
 
+
+class TestTreeUrlIntoADirectory(unittest.TestCase):
+    """`.../libretro-samples/tree/master/tests/cruzes` took the whole tail as
+    the branch; nothing resolved and cruzes was skipped as having no pin."""
+
+    def test_candidates_are_prefixes_shortest_first(self):
+        self.assertEqual(
+            profile_sync.branch_candidates(
+                "https://github.com/libretro/libretro-samples/tree/master/tests/cruzes"
+            ),
+            ["master", "master/tests", "master/tests/cruzes"],
+        )
+        self.assertEqual(profile_sync.branch_candidates("https://github.com/o/r"), [])
+
+    def test_the_first_resolving_prefix_is_the_branch(self):
+        from unittest import mock
+
+        asked = []
+
+        def head(repo, cache, offline=False, branch=None):
+            asked.append(branch)
+            return "tipsha" if branch == "master" else None
+
+        profile = {"source": "https://github.com/libretro/libretro-samples/tree/master/tests/cruzes",
+                   "source_commit": "pinsha"}
+        with mock.patch.object(profile_sync.upstream, "resolve_head", side_effect=head):
+            views = profile_sync.select_views(profile, ".cache", True)
+        self.assertEqual([(v.pin, v.head) for v in views], [("pinsha", "tipsha")])
+        self.assertEqual(asked[0], "master")
+
+
+
+class TestAnUnansweringRepository(unittest.TestCase):
+    """pyxel declares source_commit, yet the skip read "no source_commit":
+    its repository answers 404. A declared upstream_gone was honoured only
+    when the forge raised GoneError, never on a plain non-answer."""
+
+    def _report(self, profile):
+        from unittest import mock
+
+        with mock.patch.object(profile_sync, "select_views", return_value=[]):
+            return profile_sync.build_report("p", profile, ".cache", True)
+
+    def test_a_declared_pin_names_the_repository(self):
+        report = self._report({"source": "https://github.com/o/r", "source_commit": "abc",
+                               "files": [{"name": "a", "source_ref": "a.c:1"}]})
+        self.assertIn("no declared repository answers", report.skipped)
+
+    def test_a_declared_gone_upstream_is_honoured(self):
+        report = self._report({"source": "https://github.com/o/r", "source_commit": "abc",
+                               "upstream_gone": "404 since 2026-10-18",
+                               "files": [{"name": "a", "source_ref": "a.c:1"}]})
+        self.assertEqual(report.skipped, "upstream gone (declared): 404 since 2026-10-18")
+
+
 if __name__ == "__main__":
     unittest.main()