shred: malformed verbose output on "000" pass #7798
Description
Steps to reproduce:
$ echo asdf > foo
$ cargo run -q shred -v -n100 foo
<SNIP>
shred: foo: pass 11/100 (b6db6d)...
shred: foo: pass 12/100 (ffffff)...
shred: foo: pass 13/100 (222222)...
shred: foo: pass 14/100 (222222)...
shred: foo: pass 15/100 (000)...
shred: foo: pass 16/100 (999999)...
<SNIP>In this example, the output like for pass 15 got mangled somehow.
I'm working on this, but wanted to document it in case I forget it later.
Found while working on #5711.