Fix a bug in PaymentRequest __str__() function
Fix a bug in PaymentRequest __str__() function

pooler/electrum-ltc,wakiyamap/electrum-mona,cryptapus/electrum,spesmilo/electrum,spesmilo/electrum,asfin/electrum,pooler/electrum-ltc,pooler/electrum-ltc,wakiyamap/electrum-mona,vialectrum/vialectrum,neocogent/electrum,neocogent/electrum,wakiyamap/electrum-mona,fujicoin/electrum-fjc,fujicoin/electrum-fjc,spesmilo/electrum,wakiyamap/electrum-mona,vialectrum/vialectrum,cryptapus/electrum,asfin/electrum,spesmilo/electrum,vialectrum/vialectrum,neocogent/electrum,asfin/electrum,fujicoin/electrum-fjc,cryptapus/electrum,pooler/electrum-ltc