rust: fix broken debug assertions

These were caught by `clippy`. It appears no one uses the debug builds, which
is how this wasn't caught before.

rust/hg-core/src/copy_tracing.rs

@@ -613,7 +613,7 b' fn compare_value('
         // eventually.
         (MergePick::Minor, true)
     } else if src_major.path == src_minor.path {
-        debug_assert!(src_major.rev != src_major.rev);
+        debug_assert!(src_major.rev != src_minor.rev);
         // we have the same value, but from other source;
         if src_major.is_overwritten_by(src_minor) {
             (MergePick::Minor, false)
@@ -623,7 +623,7 b' fn compare_value('
             (MergePick::Any, true)
         }
     } else {
-        debug_assert!(src_major.rev != src_major.rev);
+        debug_assert!(src_major.rev != src_minor.rev);
         let action = merge_case_for_dest();
         if src_minor.path.is_some()
             && src_major.path.is_none()