[BUG] core's `_build_fn_name` has unexpected interactions with reconciler's attributes

[kdgutier]

When using for a second time an object instantiated from the HierarchicalReconciliation, the attributes that its self.reconcilers store as part of their fit affect the final column names

I traced back the error to core's _build_fn_name that uses all the original and new attributes from the self.reconcilers.

This is problematic for new methods that recycle self.reconcilers.
For example the recently added bootstrap_reconcile

[kdgutier]

I added a momentary hack, by deep copying the original reconcilers that I use for _build_fn_name
and use the new reconcilers like normally used.