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

$ go version
go version go1.9 linux/amd64

Does this issue reproduce with the latest release?

yes, on 1.9

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

GOARCH="amd64"
GOBIN=""
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/home/bchenebault/DEV/git-oab.si.fr.intraorange/BU900102/ceo-be"
GORACE=""
GOROOT="/usr/local/go"
GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"
GCCGO="gccgo"
CC="gcc"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build913166031=/tmp/go-build -gno-record-gcc-switches"
CXX="g++"
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"

What did you do?

A Go select statement with reflect package function reflect.Select(...) should block until at least one of the cases can proceed and make a uniform pseudo-random choice. It appears that the behavior has changed since returned values are no longer pseudo-random in specific cases only.

Our case is the following : 2 signaling channels preceding 2 "logic" channels
https://play.golang.org/p/0TiMtsRk03

But the same version with only one channel preceding the 2 others works
https://play.golang.org/p/sy4RjEEjdg

This case perfectly works on go1.8.3 and below.

What did you expect to see?

A pseudo random distribution

What did you see instead?

A strange distribution, surely not pseudo random