yoctogit: Fix broken retryFetch logic

If the fetch fails, we try it again and then ignore the return value? I'm
not sure why this would help but regardless, this logic is just plain wrong.

This fixes the code to try again and this time, check the value. If it fails
we might resort to clobbering if enabled.

This stops teh fetcher failing but the build proceeding regardless.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
PublishLayerTarballs: Don't hang is PUBLISH_BUILDS isn't set

Currently no command is run if PUBLISH_BUILDS is set to False. This
leads to the autobuilder just hanging.

This change ensures some command is always run.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>