4b62bdf5136c174621509bf7866fbd89b61cc66a Wallet: Refactor ReserveKeyFromKeyPool for safety (Ben Woosley)
Pull request description:
ReserveKeyFromKeyPool's previous behaviour is to set nIndex to -1 if the keypool is empty, OR throw an exception for technical failures. Instead, we now return false if the keypool is empty, true if the operation succeeded. This is to make failure more easily detectable by calling code.
Backport of Core PR13252
Depends on D4207