PY-29092: Merge env vars instead of overriding in console debugger
PY-29092: Merge env vars instead of overriding in console debugger

(cherry picked from commit 8e60e21)

Elizaveta239/PyDev.Debugger,fabioz/PyDev.Debugger,fabioz/PyDev.Debugger,fabioz/PyDev.Debugger,Elizaveta239/PyDev.Debugger,fabioz/PyDev.Debugger,Elizaveta239/PyDev.Debugger,fabioz/PyDev.Debugger,Elizaveta239/PyDev.Debugger,Elizaveta239/PyDev.Debugger