* More efficiently parse shas for shaPostProcessor The shaPostProcessor currently repeatedly calls git rev-parse --verify on both backends which is fine if there is only one thing that matches a sha - however if there are multiple things then this becomes wildly inefficient. This PR provides functions for both backends which are much faster to use. Fix #16092 * Add ShaExistCache to RenderContext Signed-off-by: Andrew Thornton <[email protected]> Co-authored-by: 6543 <[email protected]>