clay: keep info in stacktrace when labeling fails
:: rewriting would violate referential transparency
::
~| %tried-to-rewrite-existing-label
- ~& "requested aeon: {<yon>}, existing aeon: {<u.yen>}"
+ ~| "requested aeon: {<yon>}, existing aeon: {<u.yen>}"
!!
::
:: Porcelain commit
