appengine dev_appserver.py未使用正确的GOPATH

Per this go blog, the appengine SDK is supposed to be able to detect GOPATH, but looks like that is not the case. Instead it is considering some path in the appengine SDK installation dir as the GOPATH. Any thoughts on how to make the appengine work with the existing GOPATH, without having to change it?

dev_appserver.py app.yaml


................

Can't find package "github.com/gorilla/context" in $GOPATH: cannot find package "github.com/gorilla/context" in any of:
/Users/muly_ae/Applications/google-cloud-sdk/platform/google_appengine/goroot-1.6/src/github.com/gorilla/context (from $GOROOT)
/Users/muly_ae/Applications/google-cloud-sdk/platform/google_appengine/gopath/src/github.com/gorilla/context (from $GOPATH)

Here is my Go env:

GOARCH="amd64"
GOBIN=""
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOOS="darwin"
GOPATH="/Users/muly_ae/go"
GORACE=""
GOROOT="/usr/local/Cellar/go/1.8.3/libexec"
GOTOOLDIR="/usr/local/Cellar/go/1.8.3/libexec/pkg/tool/darwin_amd64"
GCCGO="gccgo"
CC="clang"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -gno-record-gcc-switches -fno-common"
CXX="clang++"
CGO_ENABLED="1"
PKG_CONFIG="pkg-config"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"