Please answer these questions before submitting your issue. Thanks!

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

go version go1.10.1 openbsd/amd64

Does this issue reproduce with the latest release?

Yes

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

GOARCH="amd64"
GOBIN=""
GOCACHE="/home/gsora/.cache/go-build"
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="openbsd"
GOOS="openbsd"
GOPATH="/home/gsora/go"
GORACE=""
GOROOT="/usr/local/go"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/openbsd_amd64"
GCCGO="gccgo"
CC="cc"
CXX="c++"
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=/tmp/go-build851891915=/tmp/go-build -gno-record-gcc-switches"

What did you do?

If possible, provide a recipe for reproducing the error.
A complete runnable program is good.
A link on play.golang.org is best.

Try to use Pledge() with "execpromises" parameter.

What did you expect to see?

Pledge() taking into account the "execpromises" parameter in the syscall.

What did you see instead?

Pledge() ignoring the second parameter, because its inner workings do not work with the latest pledge(2) syscall.