Comment (by Roland Haas):

autoconf is the one using absolute paths. I tried getting rid of them once (for spaces on windows), see: https://bitbucket.org/cactuscode/cactus/branch/rhaas/spaces

So the absolute paths are not going away so easily. That colons also cause issues is new and something that may be fixable (the spaces are an issue b/c make really cannot handle spaces in paths, “just don’t use them” is what the official solution boils down to).

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Ticket URL: https://bitbucket.org/einsteintoolkit/tickets/issues/2623/colons-in-parents-parent-directory-name