Bug#955026: Xorg synaptics module enables both buttons

An additional piece of information:

If I switch from wayland to xorg X server, the touchpad works as expected.
The synaptic entires in Xorg.0.log are:

[ 64.070] (II) LoadModule: "synaptics"
[ 64.070] (II) Loading /usr/lib/xorg/modules/input/synaptics_drv.so
[ 64.071] (II) Module synaptics: vendor="X.Org Foundation"
[ 64.071] (II) Using input driver 'synaptics' for 'SynPS/2 Synaptics TouchPad'
[ 64.112] (II) synaptics: SynPS/2 Synaptics TouchPad: found clickpad property
[ 64.112] (--) synaptics: SynPS/2 Synaptics TouchPad: x-axis range 1472 - 5664 (res 42)
[ 64.112] (--) synaptics: SynPS/2 Synaptics TouchPad: y-axis range 1408 - 4682 (res 52)
[ 64.112] (--) synaptics: SynPS/2 Synaptics TouchPad: pressure range 0 - 255
[ 64.112] (--) synaptics: SynPS/2 Synaptics TouchPad: finger width range 0 - 15
[ 64.112] (--) synaptics: SynPS/2 Synaptics TouchPad: buttons: left double triple
[ 64.112] (--) synaptics: SynPS/2 Synaptics TouchPad: Vendor 0x2 Product 0x7
[ 64.112] (--) synaptics: SynPS/2 Synaptics TouchPad: touchpad found
[ 64.148] (**) synaptics: SynPS/2 Synaptics TouchPad: (accel) MinSpeed is now constant deceleration 2.5
[ 64.148] (**) synaptics: SynPS/2 Synaptics TouchPad: (accel) MaxSpeed is now 1.75
[ 64.148] (**) synaptics: SynPS/2 Synaptics TouchPad: (accel) AccelFactor is now 0.038
[ 64.148] (--) synaptics: SynPS/2 Synaptics TouchPad: touchpad found