hs-v3: Remove a BUG() when storing a descriptor in the client cache

It is possible in normal circumstances that  a client fetches a descriptor
that has a lower revision counter than the one in its cache. This can happen
due to HSDir desync.

Fixes #24976

Signed-off-by: David Goulet <dgoulet@torproject.org>

changes/bug24976

@@ -0,0 +1,5 @@
+  o Minor bugfixes (hidden service v3 client):
+    - Remove a BUG() statement which can be triggered in normal circumstances
+      where a client fetches a descriptor that has a lower revision counter
+      than the one in its cache. This can happen due to HSDir desync. Fixes
+      bug 24976; bugfix on 0.3.2.1-alpha.

src/or/hs_cache.c

@@ -624,8 +624,8 @@ cache_store_as_client(hs_cache_client_descriptor_t *client_desc)
   if (cache_entry != NULL) {
     /* If we have an entry in our cache that has a revision counter greater
      * than the one we just fetched, discard the one we fetched. */
-    if (BUG(cache_entry->desc->plaintext_data.revision_counter >
-            client_desc->desc->plaintext_data.revision_counter)) {
+    if (cache_entry->desc->plaintext_data.revision_counter >
+        client_desc->desc->plaintext_data.revision_counter) {
       cache_client_desc_free(client_desc);
       goto done;
     }