Result content missing when defined the header or footer

Define the following location and test file:
location / {
slice;
slice_arg_begin s;
slice_arg_end e;
slice_header "START";
}

tail html/test.txt
1234567890

And then request like this:
http://example.com/test.txt?s=0&e=8

the result is OK: START12345678

But then request like this:
http://example/test.txt?s=1&e=9

the result just only: START234

Is the "56789" missing?

Reproduce the issue with the shown location / configuration and html/test.txt contents. Compare the responses for s=0&e=8 and s=1&e=9, then trace the slice handling used by this configuration. Done means the second request includes the expected remaining 56789 content.

Written by the indexing model from the issue text.