Trouble setting up Go environment on OSX Yosemite

I've installed Go on OSX using Homebrew so that I could install alpaca, but keep getting errors like this:

package github.com/GeertJohan/go.rice/rice
	imports github.com/GeertJohan/go.incremental
	imports github.com/GeertJohan/go.rice/embedded
	imports github.com/akavel/rsrc/binutil
	imports github.com/akavel/rsrc/coff
	imports github.com/daaku/go.zipexe
	imports github.com/jessevdk/go-flags
	imports github.com/robertkrimen/terst
	imports testing: unrecognized import path "testing"
package github.com/GeertJohan/go.rice/rice
	imports github.com/GeertJohan/go.incremental
	imports github.com/GeertJohan/go.rice/embedded
	imports github.com/akavel/rsrc/binutil
	imports github.com/akavel/rsrc/coff
	imports github.com/daaku/go.zipexe
	imports github.com/jessevdk/go-flags
	imports github.com/robertkrimen/terst
	imports bitbucket.org/kardianos/osext
	imports bitbucket.org/pkg/inflect
	imports unicode: unrecognized import path "unicode"
make: *** [deps] Error 1

Googling around it seems the issue is with my go environment, but I can't seem to figure out how to resolve this. Here's what I see when I run go env:

GOARCH="amd64"
GOBIN=""
GOCHAR="6"
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOOS="darwin"
GOPATH="/Users/mc/go"
GORACE=""
GOROOT="/Users/mc/go/packages"
GOTOOLDIR="/Users/mc/go/packages/pkg/tool/darwin_amd64"
CC="clang"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fno-common"
CXX="clang++"
CGO_ENABLED="1"

What am I getting wrong here?

Okay, @not_a_golfer 's comment helped me figure this out -- the GOROOT needs to be where brew installed Go.

In my case export GOROOT=/usr/local/Cellar/go/1.4.1/libexec resolved it.

GOROOT="/Users/mc/go/packages" is incorrect.

You should not have to set your GOROOT. checkout out this blog post by Dave Cheney.