os: TestChtimes failure on OSX with Go 1.10: AccessTime didn't go backwards

[flowchartsman]

Please answer these questions before submitting your issue. Thanks!

What version of Go are you using (go version)?

go version go1.10 darwin/amd64

Does this issue reproduce with the latest release?

Yes

What operating system and processor architecture are you using (go env)?

GOBIN=""
GOCACHE="/Users/me/Library/Caches/go-build"
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOOS="darwin"
GOPATH="/Users/me/go"
GORACE=""
GOROOT="/Users/me/opt/go"
GOTMPDIR=""
GOTOOLDIR="/Users/me/opt/go/pkg/tool/darwin_amd64"
GCCGO="gccgo"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/cf/y_tt0zms6nx39x08k23y5zsr0000gn/T/go-build648291915=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

$ GOROOT_BOOTSTRAP=~/opt/go-bootstrap ./all.bash

What did you expect to see?

(tests pass)

What did you see instead?

--- FAIL: TestChtimes (0.00s)
        os_test.go:1200: AccessTime didn't go backwards; was=2018-02-20 14:13:29.321904999 +0200 EET, after=2018-02-20 14:13:29.322166175 +0200 EET
FAIL
FAIL    os      0.759s

[bradfitz]

Which filesystem are you using? (or the output of diskutil list if unsure)

[flowchartsman]

/dev/disk0 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *251.0 GB   disk0
   1:                        EFI EFI                     209.7 MB   disk0s1
   2:                 Apple_APFS Container disk1         250.8 GB   disk0s2

/dev/disk1 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +250.8 GB   disk1
                                 Physical Store disk0s2
   1:                APFS Volume Macintosh HD            150.1 GB   disk1s1
   2:                APFS Volume Preboot                 21.4 MB    disk1s2
   3:                APFS Volume Recovery                509.8 MB   disk1s3
   4:                APFS Volume VM                      8.6 GB     disk1s4

[flowchartsman]

Interestingly, it's been consistent during the testing run by all.bash, but it does not appear to fail consistently when I run the test manually:

$ pwd
/Users/me/opt/go/src/os
$ git status
HEAD detached at go1.10
nothing to commit, working tree clean
$ go version
go version go1.10 darwin/amd64
$ go test -run TestChtimes
PASS
ok      os      0.028s

$ go test -run TestChtimes -count 100
--- FAIL: TestChtimes (0.00s)
        os_test.go:1200: AccessTime didn't go backwards; was=2018-02-21 13:53:12.63839082 +0200 EET, after=2018-02-21 13:53:12.638618044 +0200 EET
--- FAIL: TestChtimes (0.00s)
        os_test.go:1200: AccessTime didn't go backwards; was=2018-02-21 13:53:12.6494289 +0200 EET, after=2018-02-21 13:53:12.649672743 +0200 EET
--- FAIL: TestChtimes (0.00s)
        os_test.go:1200: AccessTime didn't go backwards; was=2018-02-21 13:53:12.668288294 +0200 EET, after=2018-02-21 13:53:12.668477346 +0200 EET
--- FAIL: TestChtimes (0.00s)
        os_test.go:1200: AccessTime didn't go backwards; was=2018-02-21 13:53:12.669726791 +0200 EET, after=2018-02-21 13:53:12.66993502 +0200 EET
--- FAIL: TestChtimes (0.00s)
        os_test.go:1200: AccessTime didn't go backwards; was=2018-02-21 13:53:12.671818229 +0200 EET, after=2018-02-21 13:53:12.672012707 +0200 EET
--- FAIL: TestChtimes (0.00s)
        os_test.go:1200: AccessTime didn't go backwards; was=2018-02-21 13:53:12.695041142 +0200 EET, after=2018-02-21 13:53:12.69530369 +0200 EET
--- FAIL: TestChtimes (0.00s)
        os_test.go:1200: AccessTime didn't go backwards; was=2018-02-21 13:53:12.700318567 +0200 EET, after=2018-02-21 13:53:12.700582796 +0200 EET
--- FAIL: TestChtimes (0.00s)
        os_test.go:1200: AccessTime didn't go backwards; was=2018-02-21 13:53:12.70939443 +0200 EET, after=2018-02-21 13:53:12.709634365 +0200 EET
FAIL
exit status 1
FAIL    os      0.110s
# 8 failures

$ go test -run TestChtimes -count 100
--- FAIL: TestChtimes (0.00s)
        os_test.go:1200: AccessTime didn't go backwards; was=2018-02-21 13:54:56.998914072 +0200 EET, after=2018-02-21 13:54:56.99908879 +0200 EET
--- FAIL: TestChtimes (0.00s)
        os_test.go:1200: AccessTime didn't go backwards; was=2018-02-21 13:54:57.005143503 +0200 EET, after=2018-02-21 13:54:57.005366258 +0200 EET
--- FAIL: TestChtimes (0.00s)
        os_test.go:1200: AccessTime didn't go backwards; was=2018-02-21 13:54:57.025131058 +0200 EET, after=2018-02-21 13:54:57.025365872 +0200 EET
--- FAIL: TestChtimes (0.00s)
        os_test.go:1200: AccessTime didn't go backwards; was=2018-02-21 13:54:57.044399788 +0200 EET, after=2018-02-21 13:54:57.044632386 +0200 EET
--- FAIL: TestChtimes (0.00s)
        os_test.go:1200: AccessTime didn't go backwards; was=2018-02-21 13:54:57.048286199 +0200 EET, after=2018-02-21 13:54:57.048481842 +0200 EET
--- FAIL: TestChtimes (0.00s)
        os_test.go:1200: AccessTime didn't go backwards; was=2018-02-21 13:54:57.050627292 +0200 EET, after=2018-02-21 13:54:57.050833052 +0200 EET
--- FAIL: TestChtimes (0.00s)
        os_test.go:1200: AccessTime didn't go backwards; was=2018-02-21 13:54:57.052161678 +0200 EET, after=2018-02-21 13:54:57.052342728 +0200 EET
--- FAIL: TestChtimes (0.00s)
        os_test.go:1200: AccessTime didn't go backwards; was=2018-02-21 13:54:57.054604821 +0200 EET, after=2018-02-21 13:54:57.05485316 +0200 EET
--- FAIL: TestChtimes (0.00s)
        os_test.go:1200: AccessTime didn't go backwards; was=2018-02-21 13:54:57.056101792 +0200 EET, after=2018-02-21 13:54:57.056310886 +0200 EET
--- FAIL: TestChtimes (0.00s)
        os_test.go:1200: AccessTime didn't go backwards; was=2018-02-21 13:54:57.058721085 +0200 EET, after=2018-02-21 13:54:57.058966065 +0200 EET
--- FAIL: TestChtimes (0.00s)
        os_test.go:1200: AccessTime didn't go backwards; was=2018-02-21 13:54:57.065058542 +0200 EET, after=2018-02-21 13:54:57.065261722 +0200 EET
--- FAIL: TestChtimes (0.00s)
        os_test.go:1200: AccessTime didn't go backwards; was=2018-02-21 13:54:57.081118991 +0200 EET, after=2018-02-21 13:54:57.081284904 +0200 EET
FAIL
exit status 1
FAIL    os      0.115s
# 12 failures