MastForest::merge for one forest does not behave like identity

[paracetamolo]

Packages versions

miden-vm: 0.12.0

Bug description

When MastForest::merge takes a single element it should return it unchanged. In some cases like the program built in miden-vm/assembly/src/assembler/tests.rs:nested_blocks the returned forest is different than the original.

This is a minor issue, just documenting it because it caused an unrelated piece of code to fail (the mast vendoring).

How can this be reproduced?

No response

Relevant log output