Error: basic_string::_M_construct null not valid

[fedya]

trying to bootstrap minimal chroot with custom repo and got such error

Error: basic_string::_M_construct null not valid

strace

[pid 532772] write(6, "2021-10-29T09:46:16+0000 SUBDEBUG \nTraceback (most recent call last):\n  
File \"/usr/lib/python3.10/site-packages/dnf/repo.py\", line 574, in load\n  
File \"/usr/lib64/python3.10/site-packages/libdnf/repo.py\", line 331, in load\nRuntimeError: basic_string::_M_construct null not valid\n\nDuring handling of the above exception, another exception occurred:\n\nTraceback (most recent call last):\n  File \"/usr/lib/python3.10/site-packages/dnf/cli/main.py\", line 67, in main\n  File \"/usr/lib/python3.10/site-packages/dnf/cli/main.py\", line 108, in _main\n  File \"/usr/lib/python3.10/site-packages/dnf/cli/main.py\", line 124, in cli_run\n  File \"/usr/lib/python3.10/site-packages/dnf/cli/cli.py\", line 1052, in run\n  File \"/usr/lib/python3.10/site-packages/dnf/cli/commands/makecache.py\", line 50, in run\n  File \"/usr/lib/python3.10/site-packages/dnf/base.py\", line 370, in update_cache\n  File \"/usr/lib/python3.10/site-packages/dnf/base.py\", line 399, in fill_sack\n  File \"/usr/lib/python3.10/site-packages/dnf/base."..., 1178) = 1178
[pid 532772] getpid()                   = 532772
[pid 532772] write(2, "Error: basic_string::_M_construct null not valid\n", 49Error: basic_string::_M_construct null not valid
) = 49

[j-mracek]

May I ask you for reproducer that trigger the issue. It will make fixing easier.