retry_if_exception_message: use re.search for the match= pattern so it finds the regex anywhere in the message

[HrachShah]

Bug

retry_if_exception_message(match=...) compiled the user's regex and called re.Pattern.match(), which only matches at the start of the string. The parameter is named match and the docstring just says "matches" — so users reasonably expect the pattern to be found anywhere in the exception message, the same way re.search does. With the current implementation, a user who wrote:

@retry(retry=retry_if_exception_message(match="rate limit"))
def fetch(): ...

got a retry on ValueError("rate limit hit") (works by accident) but no retry on ValueError("HTTP 429: rate limit hit") (pattern not at the start). That second case is the common real-world one and is exactly the kind of message HTTP libraries produce.

Fix

Use self.match.search(...) instead of self.match.match(...) in retry_if_exception_message._check. The behaviour of message= (full-string equality) is unchanged.

Test

Added test_retry_if_exception_message_match_finds_pattern_anywhere plus a module-level helper that raises CustomError("HTTP 429: rate limit exceeded") and matches on "limit exceeded" (which does not occur at position 0). The pre-existing test test_retry_if_exception_message_match still passes — it uses a pattern prefixed with derived_message[:3] + ".*" so both re.match and re.search accept it.

Full suite: 128 passed.