time: support colon at start of TZ value
According to POSIX, there are three formats for TZ variable. When
it refers to timezone file, it should starts with a colon. This commit
removes the colon if it exists, so that it keeps compatible with both
the spec and the old behavior.
Change-Id: I30cfeaea530d24e174de309952338cb1146694a5
GitHub-Last-Rev:
11d83d11ca2eca9d542036cf5e23559388fd323e
GitHub-Pull-Request: golang/go#27570
Reviewed-on: https://go-review.googlesource.com/c/go/+/134217
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Trust: Dmitri Shuralyov <dmitshur@golang.org>