test: tweak v1-copy test to work around a msvc asan bug

Hopefully the last we hear from https://developercommunity.visualstudio.com/t/Address-sanitizer-in-Release-may-introdu/10314256

Author: iboB

test/v1compat/tv1-copy.cpp

@@ -124,22 +124,23 @@ TEST_CASE("obj_copy_fail") {
     // v2!: all exceptions here are object_error
     CHECK_THROWS_AS(object foo = o1.copy(), dynamix::object_error);
 
+    object empty;
     object o2;
     mutate(o2)
         .add<special_copy>()
         .add<trivial_copy>()
         .add<no_copy>();
 
     CHECK(!o2.copyable());
-    CHECK_THROWS_AS(o1.copy_from(o2), dynamix::object_error);
+    CHECK_THROWS_AS(empty.copy_from(o2), dynamix::object_error);
 
     object o3;
     mutate(o3)
         .add<trivial_copy>()
         .add<no_copy>();
 
     CHECK(!o3.copyable());
-    CHECK_THROWS_AS(o1.copy_from(o3), dynamix::object_error);
+    CHECK_THROWS_AS(empty.copy_from(o3), dynamix::object_error);
 
     object o4;
     mutate(o4)
@@ -150,4 +151,3 @@ TEST_CASE("obj_copy_fail") {
 
     CHECK_THROWS_AS(o4.copy_from(o1), dynamix::object_error);
 }
-