lfutil: provide a hint if the largefiles/lfs cache path cannot be determined...
lfutil: provide a hint if the largefiles/lfs cache path cannot be determined
A coworker hit this error using an LFS repo in a stripped down environment, and
didn't know how to resolve it.
The final conditional is a bit fast and loose, but there is currently no 'posix'
test in hghave, and it doesn't seem like it's worth adding for this since I
think Windows is the only non-POSIX platform we run tests on.
Differential Revision:
https://phab.mercurial-scm.org/D8145
