Yocto 2.4

Move OpenBMC to Yocto 2.4(rocko)

Tested: Built and verified Witherspoon and Palmetto images
Change-Id: I12057b18610d6fb0e6903c60213690301e9b0c67
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/import-layers/yocto-poky/scripts/lib/devtool/sdk.py b/import-layers/yocto-poky/scripts/lib/devtool/sdk.py
index e8bf0ad..f46577c 100644
--- a/import-layers/yocto-poky/scripts/lib/devtool/sdk.py
+++ b/import-layers/yocto-poky/scripts/lib/devtool/sdk.py
@@ -155,7 +155,7 @@
         if os.path.exists(os.path.join(basepath, 'layers/.git')):
             out = subprocess.check_output("git status --porcelain", shell=True, cwd=layers_dir)
             if not out:
-                ret = subprocess.call("git fetch --all; git reset --hard", shell=True, cwd=layers_dir)
+                ret = subprocess.call("git fetch --all; git reset --hard @{u}", shell=True, cwd=layers_dir)
             else:
                 logger.error("Failed to update metadata as there have been changes made to it. Aborting.");
                 logger.error("Changed files:\n%s" % out);