`make test` says "cannot find package"

$ make test
... snip ...
go test  -run=. -test.v -test.timeout=440s -covermode=count -coverprofile=capi.out ./api || exit 1
api/admin.go:16:2: cannot find package "github.com/alecthomas/log4go" in any of:
    /usr/lib/go/src/github.com/alecthomas/log4go (from $GOROOT)
    /home/root3/go/src/github.com/alecthomas/log4go (from $GOPATH)
... snip ...
make: *** [Makefile:160: test-server] Error 1

After installing those dependencies I had this error:

$ make test
... snip ...
go test  -run=. -test.v -test.timeout=440s -covermode=count -coverprofile=capi.out ./api || exit 1
# _/home/root3/mattermost/api
/tmp/go-build470298366/_/home/root3/mattermost/api/_test/_obj_test/context.go:113: cannot assign "github.com/mattermost/platform/vendor/github.com/nicksnyder/go-i18n/i18n".TranslateFunc to c.T (type "github.com/nicksnyder/go-i18n/i18n".TranslateFunc) in multiple assignment
/tmp/go-build470298366/_/home/root3/mattermost/api/_test/_obj_test/context.go:255: cannot use c.T (type "github.com/nicksnyder/go-i18n/i18n".TranslateFunc) as type "github.com/mattermost/platform/vendor/github.com/nicksnyder/go-i18n/i18n".TranslateFunc in argument to c.Err.Translate
/tmp/go-build470298366/_/home/root3/mattermost/api/_test/_obj_test/websocket_handler.go:27: cannot use conn.T (type "github.com/nicksnyder/go-i18n/i18n".TranslateFunc) as type "github.com/mattermost/platform/vendor/github.com/nicksnyder/go-i18n/i18n".TranslateFunc in assignment
FAIL    _/home/root3/mattermost/api [build failed]
make: *** [Makefile:160: test-server] Error 1

Any idea?

$ uname -srvmo
Linux 4.5.4-1-ARCH #1 SMP PREEMPT Wed May 11 22:21:28 CEST 2016 x86_64 GNU/Linux