Building Machine fails

I’m building the machine from source. I run:

sudo make VERBOSE=1

output:

/home/utcloud/go/src/github.com/docker/machine/version (from $GOPATH)
mk/build.mk:28: recipe for target 'build-x' failed
make: *** [build-x] Error 1

build.mk file:

extension = $(patsubst windows,.exe,$(filter windows,$(1)))

# Valid target combinations
VALID_OS_ARCH := "[darwin/amd64][linux/amd64][linux/arm][linux/arm64][openbsd/amd64][windows/amd64][windows/386]"

os.darwin := Darwin
os.linux := Linux
os.openbsd := OpenBSD
os.windows := Windows

arch.amd64 := x86_64
arch.arm := armhf
arch.arm64 := aarch64
arch.386 := i386

define gocross
	$(if $(findstring [$(1)/$(2)],$(VALID_OS_ARCH)), \
	GOOS=$(1) GOARCH=$(2) CGO_ENABLED=0 \
		$(GO) build \
		-o $(PREFIX)/bin/$(PKG_NAME)-${os.$(1)}-${arch.$(2)}$(call extension,$(GOOS)) \
		-a $(VERBOSE_GO) -tags "static_build netgo $(BUILDTAGS)" -installsuffix netgo \
		-ldflags "$(GO_LDFLAGS) -extldflags -static" $(GO_GCFLAGS) ./cmd/docker-machine;)
endef


build-x: $(shell find . -type f -name '*.go')
	$(foreach GOARCH,$(TARGET_ARCH),$(foreach GOOS,$(TARGET_OS),$(call gocross,$(GOOS),$(GOARCH))))

$(PREFIX)/bin/$(PKG_NAME)$(call extension,$(GOOS)): $(shell find . -type f -name '*.go')
	$(GO) build \
	-o $@ \
	$(VERBOSE_GO) -tags "$(BUILDTAGS)" \
	-ldflags "$(GO_LDFLAGS)" $(GO_GCFLAGS) ./cmd/docker-machine

build: $(PREFIX)/bin/$(PKG_NAME)$(call extension,$(GOOS))

Ubuntu 18.04
the release I’m using can be cloned using git clone -b "fishrockz/awsIOPS" git@github.com:fishrockz/machine.git docker-machine