Only load the newest version of an agent's inventory cache

This isn't entirely correct, but without a cross-platform way to
map specifically the requesting viewer to a cache directory this
is the least annoying thing we can do.

hippolyzer/lib/proxy/inventory_manager.py

@@ -1,3 +1,6 @@
+import datetime as dt
+
+from hippolyzer.lib.base.helpers import get_mtime
 from hippolyzer.lib.client.inventory_manager import InventoryManager
 from hippolyzer.lib.client.state import BaseClientSession
 from hippolyzer.lib.proxy.viewer_settings import iter_viewer_cache_dirs
@@ -6,7 +9,20 @@ from hippolyzer.lib.proxy.viewer_settings import iter_viewer_cache_dirs
 class ProxyInventoryManager(InventoryManager):
     def __init__(self, session: BaseClientSession):
         super().__init__(session)
+        newest_cache = None
+        newest_timestamp = dt.datetime(year=1970, month=1, day=1, tzinfo=dt.timezone.utc)
+        # Look for the newest version of the cached inventory and use that.
+        # Not foolproof, but close enough if we're not sure what viewer is being used.
         for cache_dir in iter_viewer_cache_dirs():
             inv_cache_path = cache_dir / (str(session.agent_id) + ".inv.llsd.gz")
             if inv_cache_path.exists():
-                self.load_cache(inv_cache_path)
+                mod = get_mtime(inv_cache_path)
+                if not mod:
+                    continue
+                mod_ts = dt.datetime.fromtimestamp(mod, dt.timezone.utc)
+                if mod_ts <= newest_timestamp:
+                    continue
+                newest_cache = inv_cache_path
+
+        if newest_cache:
+            self.load_cache(newest_cache)