Set the release branch variable
Set the release branch variable

when using the current branch, otherwise we'll try to check out
the wrong thing

matrix-org/matrix-js-sdk,krombel/matrix-js-sdk,matrix-org/matrix-js-sdk,krombel/matrix-js-sdk,krombel/matrix-js-sdk,matrix-org/matrix-js-sdk,williamboman/matrix-js-sdk,williamboman/matrix-js-sdk,matrix-org/matrix-js-sdk,williamboman/matrix-js-sdk