devtool: upgrade: fetch remote repository before checking out new revision
If we're upgrading a recipe that fetches from git, and we've simply
fetched a tarball of the repo instead of directly from the upstream repo
(this can happen if you have PREMIRRORS set up as in poky with a core recipe,
e.g. kernelshark) then we won't have any new revisions, and the checkout
will fail with "fatal: reference is not a tree: <hash>". To avoid this,
do a "git fetch" before checking out the new revision.
(From OE-Core master rev:
c4daebf3fe797a8063dcbc2ab229be2fbedc8134)
Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
