bug#54001: 29.0.50; abbreviate-file-name has side-effects

[Jim Porter]

On 2/14/2022 11:48 AM, Stefan Monnier via Bug reports for GNU Emacs, the 
Swiss army knife of text editors wrote:
> > > I suggest we take a step back and think of how to get that feature
> > > without having to contact any remote host during `abbreviate-file-name`.
> > > Maybe we can do that by making Tramp opportunistically add entries to
> > > `directory-abbrev-alist` when it performs expansion?
[snip]
> > Another option might be to store the abbreviations for a given
> > file-name-handler somewhere internally and consult that when calling that
> > file-name-handler's implementation of `abbreviate-file-name'.
>
> That would work as well.

Looking at my original patch again, this value is already cached as a 
Tramp connection property named "home-directory". If the code were 
changed to set that connection property in a more-appropriate place, and 
`tramp-handle-abbreviate-file-name' simply *reads* that connection 
property, then I think that should resolve this issue.