use a simple script instead of cargo clone.

src/test/run-make/git_clone_sha1.sh

@@ -0,0 +1,23 @@
+#!/bin/bash -x
+
+# Usage: $0 project_name url sha1
+# Get the crate with the specified sha1.
+#
+# all arguments are required.
+#
+# See below link for git usage:
+# https://stackoverflow.com/questions/3489173/how-to-clone-git-repository-with-specific-revision-changeset/14091182#14091182
+
+# Mandatory arguments:
+PROJECT_NAME=$1
+URL=$2
+SHA1=$3
+
+function err_exit() {
+    echo "ERROR:" $*
+    exit 1
+}
+
+git clone $URL $PROJECT_NAME || err_exit
+cd $PROJECT_NAME || err_exit
+git reset --hard $SHA1 || err_exit

src/test/run-make/thumb-none-cortex-m/Makefile

@@ -15,9 +15,11 @@ ifneq (,$(filter $(TARGET),thumbv6m-none-eabi thumbv7em-none-eabi thumbv7em-none
 
 # We need to be outside of 'src' dir in order to run cargo
 WORK_DIR := $(RUST_TEST_TMPDIR)/run-make/$(TARGET)
+HERE := $(shell pwd)
 
 CRATE := cortex-m
-CRATE_VER := 0.5.0
+CRATE_URL := https://github.com/rust-embedded/cortex-m
+CRATE_SHA1 := a448e9156e2cb1e556e5441fd65426952ef4b927 # 0.5.0
 
 RUSTC := $(RUSTC_ORIGINAL)
 LD_LIBRARY_PATH := $(HOST_RPATH_DIR)
@@ -26,7 +28,7 @@ all:
 	env
 	mkdir -p $(WORK_DIR)
 	-cd $(WORK_DIR) && rm -rf $(CRATE)
-	cd $(WORK_DIR) && $(CARGO) clone $(CRATE) --vers $(CRATE_VER)
+	cd $(WORK_DIR) && bash -x $(HERE)/../git_clone_sha1.sh $(CRATE) $(CRATE_URL) $(CRATE_SHA1)
 	cd $(WORK_DIR) && cd $(CRATE) && $(CARGO) build --target $(TARGET) -v
 else