Fix failure of media_build build script

Hi

I was trying to run build --main-git without the --depth option and it went splat. The attached series fixes my problem, possibly not entirely correctly for all cases, in the first patch. The other two patches are small cleanups that should make things more legible.

Vincent McIntyre (3):
Use a better name for the upstream remote. Add a helper to simplify all the system-or-die calls Convert remaining system-or-die calls

 build | 76 +++++++++++++++++++++++++++++++++++++++----------------------------
 1 file changed, 44 insertions(+), 32 deletions(-)

2.7.4

Before sending I ran one-more-test... which failed. Will respin and try again later.

Vince