Unable to change temperature during heat up process

[jalalshabo]

Bug Description

Unable to change temperature of printer extruder and bed during heat up process before print.

My Configurations

The current configuration provided on this github

Steps to Reproduce

1. Start print.
2. Try to change temperature during warm up of extruder or bed

Expected behavior: [What you expect to happen]

If I remember correctly the original firmware would allow changes to temperature during warm up phase

Actual behavior: [What actually happens]

Reverts to original warm up temp until both values achieved and then will allow you to change the temperature

[Bodengriller]

which gcode do you use to set the heatup-temperature?
For Hotend:
M104
M109

Bed:
M140
M190

If you use M109/M190, which is usual to really have the desired temperature at the start of printing, it is completely normal that no changes can be made during the heating phase.
This is also the case with Marlin 1.1.9.

This command (as well as M109 and M190) can block new commands from the host, preventing remote shutdown.