Remove .keep_* special case
apk includes a special case when installed directories have a name starting with .keep_
.
if (bfile.len > 6 && memcmp(bfile.ptr, ".keep_", 6) == 0)
return 0;
The code was there since the initial commit. I don't think it provides any purpose.
I would suggest removing that code or documenting it.
CC @fabled since you committed that code