net/textproto, sync: unlock mutexes appropriately before panics
Ensure mutexes are unlocked right before panics, where defers aren’t easily usable.
Change-Id: I67c9870e7a626f590a8de8df6c8341c5483918dc
GitHub-Last-Rev:
bb8ffe538b3956892b55884fd64eadfce326f7b0
GitHub-Pull-Request: golang/go#37143
Reviewed-on: https://go-review.googlesource.com/c/go/+/218717
Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com>
Run-TryBot: Emmanuel Odeke <emm.odeke@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>