Add comment about simplifying code using to-be-released features.

Cargo.toml

@@ -28,6 +28,8 @@ lru = "0.6.6"
 memmem = "0.1"
 memoffset = "0.6"
 num_cpus = "1"
+# When bumping the version of Sequoia search the code for XXX to find
+# spots where we can take advantage of new features.
 sequoia-openpgp = "1.3"
 thiserror = "1"
 

src/keystore.rs

@@ -597,6 +597,9 @@ impl Keystore {
             // key material is not serialized so it is not considered,
             // but we want to consider secret key material.  So, we
             // need to be a bit smarter.
+            //
+            // XXX: Starting in Sequoia 1.4 we will be able to do:
+            // cert.as_tsk() == other.as_tsk().
             match (current.is_tsk(), cert.is_tsk()) {
                 (true, true) =>
                     current.clone().into_packets().collect::<Vec<_>>()