errors: Example_unwrap fails on windows, js-wasm, nacl

[cuonglm]

windows: https://storage.googleapis.com/go-build-log/2dea0128/windows-amd64-2016_91602ff3.log
nacl: https://storage.googleapis.com/go-build-log/2dea0128/nacl-amd64p32_cd2e32e1.log
js-wasm: https://storage.googleapis.com/go-build-log/2dea0128/js-wasm_6c6f1d40.log

--- FAIL: Example_unwrap (0.00s)
got:
reading config file at 1989-03-15 22:30:00 +0000 UTC: open non-existing: The system cannot find the file specified.
want:
reading config file at 1989-03-15 22:30:00 +0000 UTC: open non-existing: no such file or directory
FAIL
FAIL	errors	0.024s
ok  	expvar	0.046s
ok  	flag	0.028s
FAIL
2019/08/25 16:52:31 Failed: exit status 1


Error: tests failed: dist test failed: go_test:errors: exit status 1

[andybons]

@gopherbot please open a backport issue for 1.13

[gopherbot]

Backport issue(s) opened: #33829 (for 1.13).

Remember to create the cherry-pick CL(s) as soon as the patch is submitted to master, according to https://golang.org/wiki/MinorReleases.

[gopherbot]

Backport issue(s) opened: #33830 (for 1.13).

Remember to create the cherry-pick CL(s) as soon as the patch is submitted to master, according to https://golang.org/wiki/MinorReleases.

[gopherbot]

Change https://golang.org/cl/191541 mentions this issue: errors: fix example unwrap test

[millerresearch]

It fails on Plan 9 too.