Create the ProxyError Exception.  Raise it when an unproxy operation fails because information is wrong or not available.
Create the ProxyError Exception.  Raise it when an unproxy
operation fails because information is wrong or not available.

--HG--
extra : convert_revision : 1fd90c1291618b09752179cfa6894f1df495fffd

austinharris/gem5-riscv,samueldotj/TeeRISC-Simulator,gem5/gem5,yb-kim/gemV,briancoutinho0905/2dsampling,powerjg/gem5-ci-test,austinharris/gem5-riscv,gem5/gem5,briancoutinho0905/2dsampling,yb-kim/gemV,kaiyuanl/gem5,qizenguf/MLC-STT,TUD-OS/gem5-dtu,powerjg/gem5-ci-test,gedare/gem5,Weil0ng/gem5,cancro7/gem5,cancro7/gem5,aclifton/cpeg853-gem5,HwisooSo/gemV-update,gedare/gem5,yb-kim/gemV,KuroeKurose/gem5,joerocklin/gem5,sobercoder/gem5,sobercoder/gem5,KuroeKurose/gem5,TUD-OS/gem5-dtu,yb-kim/gemV,gem5/gem5,yb-kim/gemV,joerocklin/gem5,KuroeKurose/gem5,SanchayanMaity/gem5,markoshorro/gem5,rjschof/gem5,sobercoder/gem5,joerocklin/gem5,Weil0ng/gem5,cancro7/gem5,HwisooSo/gemV-update,zlfben/gem5,gedare/gem5,markoshorro/gem5,TUD-OS/gem5-dtu,samueldotj/TeeRISC-Simulator,rjschof/gem5,aclifton/cpeg853-gem5,kaiyuanl/gem5,powerjg/gem5-ci-test,markoshorro/gem5,qizenguf/MLC-STT,gem5/gem5,rallylee/gem5,gedare/gem5,briancoutinho0905/2dsampling,SanchayanMaity/gem5,Weil0ng/gem5,zlfben/gem5,briancoutinho0905/2dsampling,powerjg/gem5-ci-test,qizenguf/MLC-STT,kaiyuanl/gem5,rallylee/gem5,rjschof/gem5,austinharris/gem5-riscv,austinharris/gem5-riscv,samueldotj/TeeRISC-Simulator,cancro7/gem5,SanchayanMaity/gem5,austinharris/gem5-riscv,rallylee/gem5,KuroeKurose/gem5,aclifton/cpeg853-gem5,sobercoder/gem5,zlfben/gem5,markoshorro/gem5,samueldotj/TeeRISC-Simulator,Weil0ng/gem5,SanchayanMaity/gem5,kaiyuanl/gem5,Weil0ng/gem5,samueldotj/TeeRISC-Simulator,cancro7/gem5,gem5/gem5,joerocklin/gem5,yb-kim/gemV,gem5/gem5,qizenguf/MLC-STT,cancro7/gem5,SanchayanMaity/gem5,sobercoder/gem5,gedare/gem5,markoshorro/gem5,gedare/gem5,rallylee/gem5,rjschof/gem5,markoshorro/gem5,qizenguf/MLC-STT,kaiyuanl/gem5,joerocklin/gem5,SanchayanMaity/gem5,rallylee/gem5,TUD-OS/gem5-dtu,yb-kim/gemV,qizenguf/MLC-STT,aclifton/cpeg853-gem5,HwisooSo/gemV-update,briancoutinho0905/2dsampling,zlfben/gem5,aclifton/cpeg853-gem5,KuroeKurose/gem5,TUD-OS/gem5-dtu,samueldotj/TeeRISC-Simulator,zlfben/gem5,markoshorro/gem5,HwisooSo/gemV-update,aclifton/cpeg853-gem5,aclifton/cpeg853-gem5,zlfben/gem5,Weil0ng/gem5,kaiyuanl/gem5,briancoutinho0905/2dsampling,kaiyuanl/gem5,austinharris/gem5-riscv,powerjg/gem5-ci-test,samueldotj/TeeRISC-Simulator,Weil0ng/gem5,sobercoder/gem5,qizenguf/MLC-STT,gem5/gem5,joerocklin/gem5,TUD-OS/gem5-dtu,yb-kim/gemV,rjschof/gem5,powerjg/gem5-ci-test,rjschof/gem5,KuroeKurose/gem5,powerjg/gem5-ci-test,HwisooSo/gemV-update,rallylee/gem5,KuroeKurose/gem5,sobercoder/gem5,zlfben/gem5,SanchayanMaity/gem5,joerocklin/gem5,gedare/gem5,rallylee/gem5,TUD-OS/gem5-dtu,HwisooSo/gemV-update,joerocklin/gem5,cancro7/gem5,briancoutinho0905/2dsampling,austinharris/gem5-riscv,HwisooSo/gemV-update,rjschof/gem5