Test fails on 32-bit targets

[cinerea0]

When running tests on an i686 target, the following failure occurs:

---- traverse::tests::size_of_entry_data stdout ----
thread 'traverse::tests::size_of_entry_data' panicked at src/traverse.rs:315:9:
assertion `left == right` failed: the size of this should not change unexpectedly as it affects overall memory consumption
  left: 56
 right: 80
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

This failure can be seen in CI here.

Reading the assertion message, is it necessary that the size of the data be exactly 80, or just that it be less than or equal to 80?

[Byron]

Indeed, the structure shouldn't get larger without confirmation, but it can always get smaller :).
A fix would definitely be welcome!