Currently when singleflight recovers from a panic, it wraps it with the private
error type panicError. This change adds an `Unwrap` method to panicError to
allow wrapped errors to be returned.
Updates golang/go#62511
Change-Id: Ia510ad7d5881207ef71f9eb89c1766835af19b6b
Reviewed-on: https://go-review.googlesource.com/c/sync/+/526171
Auto-Submit: Bryan Mills <[email protected]>
Reviewed-by: Than McIntosh <[email protected]>
Reviewed-by: Bryan Mills <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>
