templatefuncs: do not crash because of invalid value fed to mailmap()
Ancestors of 54 2 0 Ancestors of 6 and 53 4 2 1 0 Ancestors of 5 and 44 2 0 Ancestors of 7, stop at 66 Ancestors of 7, including revs7 6 5 3 4 2 1 0 Ancestors of 7, 5 and 3, including revs7 5 3 6 4 2 1 0 Descendants of 57 8 Descendants of 5 and 36 7 8 Descendants of 5 and 45 7 8