conversion to a default valuation commodity may not happen with --infer-market-prices

[simonmichael]

I think it's a bug: when a valuation commodity is not specified, prices inferred with --infer-market-prices do not help select a default valuation commodity, as P prices would.

So conversion might not happen because no valuation commodity was detected (--debug=2 will show this). To be safe, specify the valuation commmodity, eg:

• -X EUR --infer-market-prices, not -V --infer-market-prices
• --value=then,EUR --infer-market-prices, not --value=then --infer-market-prices