cannot save mutable Georaster after changes

[AmitAronovitch]

Typical usecase for mutable georaster is for chaning properties of existing rasters:

raster=GeoRaster2.open(path, mutable=True)
raster.affine = new_affine
raster.save(path)

However, this fails with the following

telluric.georaster.GeoRaster2IOError: /tmp/tmpr3uk6ttb/overlap2.tif and /tmp/tmpr3uk6ttb/overlap2.tif identify the same dataset.

Note that this is only because of the lazy loading. If you add lazy_load=False to the open call above, everything works fine.

Possible remedies:

1. On save, if output path is equal to input and lazy_loaded: load before saving (instead of trying to copy to self)
2. On save, if it is a mutable raster, then load before saving
3. In open(), if mutable=True, then the default for lazy_load becomes True instead of False

(3) is easiest to implement, (1) may be more general, both may have confusing edge cases. Any opinions?