Where in the case of a relevant contract for the hire of goods—
the bailee would, apart from this subsection, have the right to treat the contract as repudiated by reason of a breach on the part of the bailor of a term implied by section 8, 9 or 10(2)(a) or (c) above, but
the breach is so slight that it would be unreasonable for him to do so,
... the breach is not to be treated as a breach of condition but may be treated as a breach of warranty.
This section applies unless a contrary intention appears in, or is to be implied from, the contract.
It is for the bailor to show that a breach fell within subsection (1)(b) above.