fix: follow the xenios preview branch

The pin 87b176a0 and tag v2.0.1 sit on preview (ahead 129, behind 0) and
not on the default xenios branch, which diverged (ahead 1784, behind 24).
The preview-v2.0.1 releases carry the dmg and ipa the notes name. With no
source_branch, profile_sync called the pin orphaned and listed 19 refs to
review that only measured the branch divergence. It now reads 1.

emulators/xenios.yml

@@ -3,6 +3,7 @@ type: standalone
 core_classification: community_fork
 source: "https://github.com/xenios-jp/XeniOS"
 upstream: "https://github.com/has207/xenia-edge"
+source_branch: preview
 source_commit: "87b176a078c316fde3adf67a217f0c44615b0e0d"
 upstream_commit: "07021f019cf55105bc26c0474e0b0835808353e2"
 profiled_date: "2026-08-23"
@@ -22,7 +23,7 @@ mode: standalone
 
 notes: |
   Apple-focused fork of Xenia, based on Xenia Edge at their merge base
-  07021f0 (upstream_commit), published from the xenios branch as
+  07021f0 (upstream_commit), published from the preview branch as
   xenios_macos_apple_silicon.dmg, xenios_macos_intel.dmg,
   xenios_macos_universal.dmg and xenios_ios_iphone_ipad.ipa. The macOS build
   names its bundle and executable Xenia-edge, the iOS build XeniOS

tests/test_audit_regressions.py

@@ -5788,6 +5788,18 @@ class NoProfileHashFromASecondarySource(unittest.TestCase):
         self.assertEqual(found, [])
 
 
+class XeniosFollowsThePreviewBranch(unittest.TestCase):
+    """The xenios pin 87b176a0 and tag v2.0.1 are ancestors of `preview`
+    (compare: ahead 129, behind 0) and diverged from the default `xenios`
+    branch (ahead 1784, behind 24). Without source_branch, profile_sync read
+    the pin as orphaned and 19 refs as moved by the branch divergence."""
+
+    def test_the_profile_names_the_branch_its_pin_is_on(self):
+        profile = yaml.safe_load((ROOT / "emulators" / "xenios.yml").read_text(encoding="utf-8"))
+        self.assertEqual(profile.get("source_branch"), "preview")
+        self.assertNotIn("from the xenios branch", profile.get("notes", ""))
+
+
 class AHashScanLabelNamesNoOtherDump(unittest.TestCase):
     """A core that finds its firmware by content names no file, so each
     entry name is a label. ares labelled its Famicom Disk System revision