remove scp syntax

[ThomasWaldmann]

borg uses regexes to parse the location argument given to it on the commandline.

these regexes are a rather complex and at least the scp-style location regex also tends to mismatches, because it is used for:

• local repos (just giving a fs path as the repo)
• remote repos (which can be also given via the ssh:// url syntax, which is less limited and clearly a remote repo)

that the user often can also give an archive name within a LOCATION specifier makes it even a bit more complex, but that is the topic of #948.

one more bad thing about scp-style is that one can not give a ssh port within it. so we also need docs / FAQ entries telling the user to not use that style if the port is not 22. also we need examples for both styles...

so, the plan is to just remove scp-style syntax. less code, less docs, less hard to debug/fix regex issues.

obviously this is a breaking change as users who use that style will have to edit their scripts / configs to use ssh url style.

bounty: https://app.bountysource.com/issues/108445136-remove-scp-syntax

[ThomasWaldmann]

btw, in case somebody is wondering about the USD 41.85 bounty amount: that was just the remainder before the organisation funds went to zero.

[ThomasWaldmann]

Crap, I was a little fast with merging this.

The idea was to merge this IF the other breaking changes are also merged.
But anyway, either we do that or we'll revert this change later again.