dispatch: properly handle relative path aliases used with -R (issue2376)
This ensures the repo config is read relative to the repo root during
dispatch.
Ancestors of 54 2 0 Ancestors of 6 and 53 4 2 1 0 Ancestors of 5 and 44 2 0 Descendants of 57 8 Descendants of 5 and 36 7 8 Descendants of 5 and 45 7 8