os/exec: TestExtraFiles failures on illumos-amd64 builder

[bcmills]

--- FAIL: TestExtraFiles (0.73s)
    exec_test.go:696: Run: exit status 1
        --- stdout:
        leaked parent file. fd = 5; want 4
        readlink("/proc/self/fd/4") = "", readlink /proc/self/fd/4: no such file or directory
        943395:	/var/tmp/workdir-host-illumos-amd64-jclulow/tmp/TestExtraFiles30452030
          Current rlimit: 65536 file descriptors
           0: S_IFCHR mode:0666 dev:574,63 ino:698458753 uid:0 gid:3 rdev:38,2
              O_RDONLY|O_LARGEFILE
              /dev/null
              offset:0
           1: S_IFIFO mode:0000 dev:571,0 ino:277563782 uid:84001 gid:84001 rdev:0,0
              O_RDWR
           2: S_IFIFO mode:0000 dev:571,0 ino:277563783 uid:84001 gid:84001 rdev:0,0
              O_RDWR
           3: S_IFREG mode:0600 dev:90,65612 ino:225335 uid:84001 gid:84001 size:12
              O_RDWR|O_CREAT|O_EXCL|O_LARGEFILE
              /var/tmp/workdir-host-illumos-amd64-jclulow/tmp/663528942
              offset:12
           5: S_IFREG mode:0755 dev:90,65612 ino:225339 uid:84001 gid:84001 size:2273603
              O_RDONLY|O_LARGEFILE FD_CLOEXEC
              /var/tmp/workdir-host-illumos-amd64-jclulow/tmp/TestExtraFiles304520309/001/read3.exe
              offset:0
           6: S_IFPORT mode:0000 dev:585,0 uid:84001 gid:84001 size:0
           7: S_IFIFO mode:0000 dev:571,0 ino:277563785 uid:84001 gid:84001 rdev:0,0
              O_RDWR|O_NONBLOCK FD_CLOEXEC
        --- stderr:
FAIL
FAIL	os/exec	1.660s

2020-11-07T14:23:20-bb9a96d/illumos-amd64
2020-11-05T23:21:33-ecc3f51/illumos-amd64
2020-11-03T23:05:51-e1b305a/illumos-amd64
2020-10-29T22:44:49-f43e012/illumos-amd64
2020-10-29T15:58:40-ddc7e1d/illumos-amd64
2020-10-29T08:08:26-d9725f5/illumos-amd64
2020-10-28T17:08:06-e3c58bb/illumos-amd64
2020-10-28T16:55:17-d4c1ad8/illumos-amd64
2020-10-28T04:33:41-c95bd2e/illumos-amd64
2020-10-23T20:54:30-5cd4390/illumos-amd64
2020-10-23T14:18:13-44dbeaf/illumos-amd64
2020-10-21T19:08:53-b2a8317/illumos-amd64
2020-10-19T14:55:41-19f6422/illumos-amd64
2020-10-16T19:13:40-41162be/illumos-amd64
2020-10-13T01:12:09-ec095f1/illumos-amd64
2020-10-12T18:31:22-2f4368c/illumos-amd64
2020-10-12T17:22:19-3736957/illumos-amd64
2020-10-12T09:28:40-e92ce92/illumos-amd64
2020-10-07T14:57:54-67edc0e/illumos-amd64
2020-10-05T15:24:30-6f2c92e/illumos-amd64
2020-10-02T10:48:33-8f1c990/illumos-amd64
2020-10-02T08:52:16-15bf061/illumos-amd64
2020-10-01T20:36:41-c78c79f/illumos-amd64
2020-09-29T16:30:26-39dde09/illumos-amd64
2020-09-29T10:52:55-815a5e2/illumos-amd64
2020-08-17T04:56:56-f979d07/illumos-amd64
2020-06-03T14:08:41-58f017b/illumos-amd64
2020-05-29T14:33:50-65f514e/illumos-amd64

CC @ianlancetaylor; see previously #25628

[jclulow]

Pardon me, but is this a duplicate of #42431 ?

[bcmills]

Indeed it is!

[bcmills]

Duplicate of #42431