addurls Formatter - provide value repr in exception

[yarikoptic]

Desired to help figure reason out. Ref: ReproNim/datalad-nda#1

[yarikoptic]

Eh, Macs on appveyor seems to be stuck at
datalad.core.distributed.tests.test_push.test_push_subds_no_recursion ...

eh heh... Unrelated and new?

[yarikoptic]

ok, will proceed -- minor and covered by a test

[yarikoptic]

FTR: fetched logs from appveyor just say that those runs failed but do not have record for the test on which they stalled

(git)smaug:/mnt/datasets/datalad/ci/logs/2021/07[master]git
$> tail -n 10 30/pr/5850/3dba19f/appveyor-6336-failed/*
==> 30/pr/5850/3dba19f/appveyor-6336-failed/8wypvvxuwsrxt3jd.txt <==
[00:08:43] datalad.distribution.tests.test_create_sibling.test_local_path_target_dir ... ok
[00:09:07] datalad.distribution.tests.test_create_sibling.test_local_relpath ... ok
[00:10:05] datalad.distribution.tests.test_create_sibling.test_non_master_branch ... ok
[00:10:05] datalad.distribution.tests.test_create_sibling.test_target_ssh_simple ... SKIP: Testrepo setup is broken on AppVeyor
[00:10:05] datalad.distribution.tests.test_create_sibling.test_target_ssh_recursive(True,) ... SKIP: Testrepo setup is broken on AppVeyor
[00:10:05] datalad.distribution.tests.test_create_sibling.test_target_ssh_recursive(False,) ... SKIP: Testrepo setup is broken on AppVeyor
[00:10:05] datalad.distribution.tests.test_create_sibling.test_target_ssh_since(True,) ... SKIP: Testrepo setup is broken on AppVeyor
[00:10:05] datalad.distribution.tests.test_create_sibling.test_target_ssh_since(False,) ... SKIP: Testrepo setup is broken on AppVeyor
[00:10:18] datalad.distribution.tests.test_create_sibling.test_failon_no_permissions(True,) ... ok
[00:10:24] datalad.distribution.tests.test_create_sibling.test_failon_no_permissions(False,) ... ok

==> 30/pr/5850/3dba19f/appveyor-6336-failed/fmp46vtuggc3htp6.txt <==
[00:14:01] get(ok): sub/file2.txt (file) [from store-storage...]
[00:14:01] action summary:
[00:14:01]   configure-sibling (ok: 1)
[00:14:01]   get (ok: 2)
[00:14:01]   install (ok: 1)
[00:14:01] nothing to save, working tree clean
[00:14:02] nothing to save, working tree clean
[00:14:02] ok
[00:14:05] datalad.core.distributed.tests.test_push.test_push_git_annex_branch_when_no_data ... ok
[00:14:53] datalad.core.distributed.tests.test_push.test_push_recursive ... ok
$> grep test_push_subds_no_recursion 30/pr/5850/3dba19f/appveyor-6336-failed/*

let's hope that it was something intermittent