rhg: in path_encode, be a bit more conservative about memory usage
Use [shrink_to_fit] to match the previous behavior more closely,
and potentially save (a tiny bit) of memory.
FWIW, I suspect this is unnecessary, but this whole MR is
about simplifying things while preserving any existing
optimizations.
edition = "2018"
max_width = 79
wrap_comments = true
error_on_line_overflow = true