Bug preventing using custom cache without state flag

[dethodav]

When a cache file is provided, but no state flag is specified, the analyzable segments are calculated using this function call:

pyomicron/omicron/cli/process.py

Line 708 in 42c2a51

segs = segments.get_frame_segments(ifo, frametype, datastart, dataend)

Since no frame type is needed when using a cache file, this returns an empty segment list. This then results in a runtime error at the following line:

pyomicron/omicron/cli/process.py

Line 829 in 42c2a51

raise RuntimeError("No analysable segments found")

This can be avoided by providing a state flag to calculate the analyzable segments. However, if one is attempting to analyze user-generated data, a usable state flag may not exist. The ideal behavior when using a cache file (and no state flag) is to use the cache file itself to generate the analyzable segments.

This can be fixed by adding an extra elif statement for this situation, which uses gwpy.io.cache.cache_segments() to calculate the required segments.