[ThomasWaldmann]

--from-borg1 via ssh:// (e.g. borg transfer --from-borg1 --other-repo ssh://...) did not work with a real borg 1.x borg serve on the remote host. Every command failed with rc 82 RPC method close is not valid. The testsuite only ever ran the legacy client against borg 2's own legacy borg serve, so this went unnoticed.

Causes

1. After open, the client called info(), which borg 1.x servers do not have (Borg server is too old for info).
2. The cleanup then called close(), which always sent the close RPC. borg 1.x servers do not have that either, and the resulting error masked the first one.
3. get_manifest is also missing on borg 1.x servers.
4. borg 1.x servers pack bytes into the msgpack "raw" type, which the borg 2 client unpacks to str (surrogateescape). So e.g. the repository id and object data arrived as str, and loading the key failed with Unsupported payload type.

Fix

In LegacyRemoteRepository, for a borg 1.x server (negotiated server version < 2.0.0a1):

• use repository version 1 instead of calling info() (borg 1.x only serves v1 repositories);
• do not send the close RPC (borg 1.x closes the repository when stdin gets closed);
• get the manifest object via get, like LegacyRepository.get_manifest() does;
• convert the results of open, get, list, scan and load_key back to bytes (surrogateescape round-trips exactly).

Borg 2 servers are handled as before.

Testing

• Real borg 1.4.5 borg serve on NetBSD 11 (remote side run via a fake ssh that executes the command locally): repo-list, version, repo-create --other-repo and transfer, all with --from-borg1, for repokey and keyfile repositories. Extracting from the transferred borg 2 repository gives the original data, and the borg 1.x repository lock is released.
• New test test_remote_borg1_server: it emulates a borg 1.x server (the legacy server with borg 1.x msgpack packing, version 1.4.5, no info/close/get_manifest, closing the repository at EOF). Without the fix it fails exactly like the real borg 1.4 case. Also new: test_bytes_from_borg1.
• Full suite locally (macOS): all pass except test_migrate_lock_alive (known local macFUSE issue, fails on master too).

🤖 Generated with Claude Code

[codecov]

Codecov Report

❌ Patch coverage is 85.18519% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 88.41%. Comparing base (db0c4ac) to head (d1c7771).
⚠️ Report is 1 commits behind head on master.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
src/borg/legacy/remote.py	85.18%	3 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #10420      +/-   ##
==========================================
+ Coverage   88.38%   88.41%   +0.02%     
==========================================
  Files         103      103              
  Lines       19029    19051      +22     
  Branches     2961     2967       +6     
==========================================
+ Hits        16819    16844      +25     
+ Misses       1538     1535       -3     
  Partials      672      672              

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