prompt: pressing ctrl-R when no root_hist file is present results in a segfault

$ rm ~/.root_hist && root.exe # && press ctrl-R

#10 0x00007fc65e4c3300 in std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::length() const () from /usr/lib/x86_64-linux-gnu/libstdc++.so.6   

#11 0x00007fc65e992db7 in textinput::Text::operator= (this=0x5646d5ed1748, S=<error reading variable: Cannot access memory at address 0xffffffffffffffe8>) at ../../../root_dbg/core/textinput/src/textinput/Text.h:76

#12 0x00007fc65e9945c4 in textinput::Editor::UpdateHistSearch (this=0x5646d672c9a0, R=...) at ../../../root_dbg/core/textinput/src/textinput/Editor.cpp:130                  

#13 0x00007fc65e995d30 in textinput::Editor::ProcessCommand (this=0x5646d672c9a0, M=textinput::Editor::kCmdReverseSearch, R=...) at ../../../root_dbg/core/textinput/src/textinput/Editor.cpp:434

#14 0x00007fc65e9940ba in textinput::Editor::Process (this=0x5646d672c9a0, cmd=..., R=...) at ../../../root_dbg/core/textinput/src/textinput/Editor.cpp:65                   

#15 0x00007fc65e9a3522 in textinput::TextInput::ProcessNewInput (this=0x7fc65ec407e0 <(anonymous namespace)::TextInputHolder::getHolder()::sTIHolder>, in=..., R=...) at ../../../root_dbg/core/textinput/src/textinput/TextInput.cpp:174

#16 0x00007fc65e9a31bf in textinput::TextInput::ReadInput (this=0x7fc65ec407e0 <(anonymous namespace)::TextInputHolder::getHolder()::sTIHolder>) at ../../../root_dbg/core/textinput/src/textinput/TextInput.cpp:126

#17 0x00007fc65e992aad in Getlinem (mode=kOneChar, prompt=0x0) at ../../../root_dbg/core/textinput/src/Getline.cxx:256