When using multiple stow directories (see Multiple Stow Directories), Stow fails to “split open” tree-folding symlinks
(see Installing Packages) that point into a stow directory which is
not the one in use by the current Stow command. Before failing, it
should search the target of the link to see whether any element of the
path contains a .stow file. If it finds one, it can “learn”
about the cooperating stow directory to short-circuit the .stow
search the next time it encounters a tree-folding symlink.