current_extruder placeholder not substituted on first export

[jamagin]

Version

1.3.0-dev
Slic3r-master.2018.02.08.1593.05461b8.64bit.zip
Slic3r-1.3.0-dev-5f28ee4-x86_64.AppImage

Operating system type + version

Windows 10 (though I have also experienced this on Linux - Fedora 26)

Behavior

It may be relevant that I'm using a dual extruder printer (Qidi Tech I). This wasn't happening to me back when I used the 1.2.9 included with Fedora 26.

I'll have a model using a single extruder, my starting g-code contains

M140 S[bed_temperature] T0 ; Heat buildplate 
M104 S[temperature_[current_extruder]] T[current_extruder] ; Heat extruder
M134 T0 ; Stabilize bed temperature
M133 T[current_extruder] ; Stabilize extruder temperature

But when I initially "Export G-code", the file it receives will contain

M140 S95 T0 ; Heat buildplate 
M104 S[temperature_[current_extruder]] T[current_extruder] ; Heat extruder
M134 T0 ; Stabilize bed temperature
M133 T[current_extruder] ; Stabilize extruder temperature

However if I "Export G-code" again, the file contains:

M140 S95 T0 ; Heat buildplate 
M104 S207 T1 ; Heat extruder
M134 T0 ; Stabilize bed temperature
M133 T1 ; Stabilize extruder temperature

I experience pretty much the same thing with "send to printer" which is how I initially found this, but it seems to reproduce fine with a simple export.

(As an aside, that build plate temperature is the temperature for the first extruder (T0) which I'm not using in this print, but I think that's a separate bug/feature request.)

STL/Config (.ZIP) where problem occurs

config-and-model.zip

[ignaworn]

This is still present in 1.3.1-dev Slic3r-master.2018.06.15.1717.88d24b7.64bit.zip for Windows. I did not test other releases.