time: document the return value of time.Parse when parsing fails

[abbot]

Current implementation (as of this submission) of time.Parse always returns a zero time.Time{} value when it hits an error. It would be nice to document this and have it as a part of API, as it would simplify some use cases.

[ianlancetaylor]

We aren't going to do that. While there are no plans to return a non-zero value, for an error case we only document the non-error result values where there is special reason to do so. There is no such reason here. You can write a trivial helper function to implement whatever functionality you want.