missing env vars for "other repo" situations (borg repo-create|transfer)

Have you checked borgbackup docs, FAQ, and open GitHub issues?

Yes

Is this a BUG / ISSUE report or a QUESTION?

Suggestion

System information. For client/server mode post info for both machines.

Your borg version (borg -V).

known to be true for borg 2 beta 10 up to 12

Will be more relevant when borg2 is final/stable and borg1 repos will be converted to borg2.

Describe the problem you're observing.

When using related repos (borg repo-create --other-repo= and borg transfer --other-repo=) there may be issues due to overlapping repository access configuration.

Easiest example:

old-repo uses passphrase "ABC", new-repo uses "XYZ", or one of them no passphrase.
only 1 passphrase can be supplied via BORG_PASSPHRASE
if this was not a non-interactive script, borg would ask for the passphrase for each repo (AFAIK)
if script (without stdin) or BORG_PASSPRHASE set, the execution would fail
in this case, workaround is available like setting key passphrases to identical

But there are other conflicting settings (by variable and by commandline like:

--rsh | BORG_RSH
--remote-path | BORG_REMOTE_PATH (yes, eg repo-old can be locally accessed via user@localhost, the repo-new on remote storage)

There may be other variables/options which conflict with each other, where there may or may not be a workaround. (I just stumbled upon these.)

I am guessing that these conflicting configuration parameters will become more evident to and reported by users, when productive repositories are more often transferred from borg1 to borg2.

But maybe this is only a weird and rare edge case that I experienced.

borgbackup / borg