canonical_name dropped "es" from every -ches/-ses/-zes plural, so "caches"
became "cach" while "cache" stayed "cache" -- the singular and plural landed on
two nodes, which is the split the function exists to prevent. The same rule
split the words documentation uses most: databases/database, responses/
response, releases/release, sizes/size.
An "-es" plural cannot say whether it is cache + "s" or batch + "es", so
instead of guessing, both sides now meet at the stem: the singular endings
-che/-she/-se/-ze/-xe drop their "e" the way the plurals drop "es", and a
singular's -ie folds to -y as -ies already did (cookie/cookies). The key is a
merge key that is never shown, so it only has to agree, not be a word. alias,
canvas, atlas and bias join the words that only look plural.
Found by the naming tests CI was missing: the module had no direct tests.
