(isearch-edit-string): Remove one call to

(isearch-edit-string): Remove one call to
`isearch-push-state' not to push an inconsistent state,
but keep another correct call to `isearch-push-state'.
(isearch-ring-adjust): Call `isearch-push-state' only when
`search-ring-update' is non-nil since `isearch-edit-string'
already pushes its state.
(isearch-message): Improve matching the failed part by checking
if the original message starts with the last successful message.