Changing backing asset ID runs some checks against the old value instead of the new.

[jmjatlanta]

Some checks examine the existing backing asset's properties instead of those of the new backing asset.

The offending line is here:

bitshares-core/libraries/chain/asset_evaluator.cpp

Line 380 in 512f816

const asset_object& backing = a.bitasset_data(d).options.short_backing_asset(d);

Checks should be performed on the incoming backing bitasset, not on the existing backing bitasset.

[btsabc]

By the way ,add checking for short_backing_asset is not allowed to be set to MPA self.

[abitmore]

Fixed with #932.