[SDL2] Backspace deletes two characters (key event happens twice?)

This started happening recently; in both the main menu and in-game console pressing backspace will delete two characters. Two other most likely related problems are:

Opening the chat with t will also add a t to the editing buffer
Holding Tab to view the scoreboard won't show the scoreboard (or just really tiny) because it is rapidly opening and closing.

Linux 64-bit (Arch)
wc-ng 0.8.1 (c0ba2bcefa64694cbb1ed2e3695058e8c1d269e7)
sdl2 2.0.5-2
sdl2_image 2.0.1-1
sdl2_mixer 2.0.1-1

some debug output for the initial problem:

# backspace in chat editing line
engine/main.cpp:899 // event.key.type=768 event.key.state=1 event.key.repeat=0 keyrepeatmask= 0x2
engine/3dgui.cpp:1212 // code 8 | isdown=true
engine/textedit.h:493 // SDLK_BACKSPACE handler
engine/main.cpp:899 // event.key.type=768 event.key.state=1 event.key.repeat=1 keyrepeatmask= 0x2
engine/3dgui.cpp:1212 // code 8 | isdown=true
engine/textedit.h:493 // SDLK_BACKSPACE handler
engine/main.cpp:899 // event.key.type=769 event.key.state=0 event.key.repeat=0 keyrepeatmask= 0x2
engine/3dgui.cpp:1212 // code 8 | isdown=false

# backspace in main menu
engine/main.cpp:899 // event.key.type=768 event.key.state=1 event.key.repeat=0 keyrepeatmask= 0x1
engine/console.cpp:557 // code 8 | isdown=true
engine/console.cpp:583 // SDLK_BACKSPACE handler
engine/main.cpp:899 // event.key.type=768 event.key.state=1 event.key.repeat=1 keyrepeatmask= 0x1
engine/console.cpp:557 // code 8 | isdown=true
engine/console.cpp:583 // SDLK_BACKSPACE handler
engine/main.cpp:899 // event.key.type=769 event.key.state=0 event.key.repeat=0 keyrepeatmask= 0x1
engine/console.cpp:557 // code 8 | isdown=false

tpoechtrager / wc-ng

[SDL2] Backspace deletes two characters (key event happens twice?) #6