Note: this is the default cache implementation in borg 1.x,
it worked well, but there were some issues:
- if the local chunks cache got out of sync with the repository,
it needed an expensive rebuild from the infos in all archives.
- to optimize that, a local chunks.archive.d cache was used to
speed that up, but at the price of quite significant space needs.
AdhocCacheWithFiles replaced this with a non-persistent chunks cache,
requesting all chunkids from the repository to initialize a simplified
non-persistent chunks index, that does not do real refcounting and also
initially does not have size information for pre-existing chunks.
We want to move away from precise refcounting, LocalCache needs to die.
Also: support a "cli" env var value, that does not determine
the implementation from the env var, but rather from cli options (similar to as it was before adding BORG_CACHE_IMPL).
rephrase some warnings, fixes#5164
borg check --repair and borg recreate are now present in the code since rather long, so they are not experimental any more.
borg recreate might be used wrongly (e.g. accidentally excluding everything / not matching anything when recreating an archive). added some warning words in the docs, but it will not ask for confirmation any more.
borg check: there might be kinds of corruption borg check --repair can not fix and it might make things even worse while trying to fix. so this will still ask for confirmation, just with different wording.
general.rst and man_intro.rst both included usage_general.rst.inc, which resulted in three Sphinx warning "WARNING: duplicate label".
To prevent this we move all sections of usage_general into own include files and add a second usage_general file without the three labels.
