Index file downloads when using GCS file

[ggydush]

I've noticed that when using a GCS file with htslib, the index file is downloaded to the current working directory. Is it possible to make this download to a temporary location? I'm parallelizing reads across multiple processes, and sometimes the index gets cleaned up when it's still needed.

[daviesrob]

I didn't think we deleted index files (where they're kept at all)? Which sort of index files are you getting, and are they disappearing, or is the problem that they're getting overwritten by a later download with the same name?