wallet2: consider 6 outputs or less to be unmixable from v7

src/wallet/wallet2.cpp

@@ -8201,14 +8201,14 @@ const wallet2::transfer_details &wallet2::get_transfer_details(size_t idx) const
 std::vector<size_t> wallet2::select_available_unmixable_outputs(bool trusted_daemon)
 {
   // request all outputs with less than 3 instances
-  const size_t min_mixin = use_fork_rules(6, 10) ? 4 : 2; // v6 increases min mixin from 2 to 4
+  const size_t min_mixin = use_fork_rules(7, 10) ? 6 : use_fork_rules(6, 10) ? 4 : 2; // v6 increases min mixin from 2 to 4, v7 to 6
   return select_available_outputs_from_histogram(min_mixin + 1, false, true, false, trusted_daemon);
 }
 //----------------------------------------------------------------------------------------------------
 std::vector<size_t> wallet2::select_available_mixable_outputs(bool trusted_daemon)
 {
   // request all outputs with at least 3 instances, so we can use mixin 2 with
-  const size_t min_mixin = use_fork_rules(6, 10) ? 4 : 2; // v6 increases min mixin from 2 to 4
+  const size_t min_mixin = use_fork_rules(7, 10) ? 6 : use_fork_rules(6, 10) ? 4 : 2; // v6 increases min mixin from 2 to 4, v7 to 6
   return select_available_outputs_from_histogram(min_mixin + 1, true, true, true, trusted_daemon);
 }
 //----------------------------------------------------------------------------------------------------