should_build?: Stop doing branch name comparison
should_build?: Stop doing branch name comparison

Instead, use git merge-base to find the oldest shared point in history
and then use that as the basis of comparison.  Also, compare with
`HEAD` instead of some branch name.

[GitHub] This commit resolves #3253.

Signed-off-by: Kristofer Rye <1ed31cfd0b53bc3d1689a6fee6dbfc9507dffd22@gmail.com>

StoDevX/AAO-React-Native,StoDevX/AAO-React-Native,StoDevX/AAO-React-Native,StoDevX/AAO-React-Native,StoDevX/AAO-React-Native,StoDevX/AAO-React-Native,StoDevX/AAO-React-Native,StoDevX/AAO-React-Native,StoDevX/AAO-React-Native