gb build do not work correctly on windows (can work correctly on linux)

[makefriend8]

gb build
the same project
on windows

FATAL: command "build" failed: failed to resolve import path "github.com/matrix-org/dendrite/clientapi": import "golang.org/x/sys/windows": not found: CreateFile c:\code\go\dendrite\src\golang.org\x\sys\windows: The system cannot find the path specified.

gb env
GB_PROJECT_DIR="c:\code\go\dendrite"
GB_SRC_PATH="c:\code\go\dendrite\src;c:\code\go\dendrite\vendor\src"
GB_PKG_DIR="c:\code\go\dendrite\pkg\windows-amd64"
GB_BIN_SUFFIX="-windows-amd64"
GB_GOROOT="c:\go"

on linux
begin to download the dependency.(and work ok)