segfault if process title is not "julia"

_clean install of PyPlot v2.9.0 on Julia 1.5.3, MacOS. Python 3.8.2 was preinstalled but I never launched it before_

This runs fine:
```julia
fons@rekenmachine ~ % julia --banner=no

julia> using PyPlot

julia> plot(1:3,1:3);

julia>
```

This segfaults:
```julia
fons@rekenmachine ~ % julia --banner=no

julia> Sys.set_process_title("asdfasdf")

julia> using PyPlot

julia> plot(1:3,1:3);

signal (11): Segmentation fault: 11
in expression starting at REPL[3]:1
_ZNK7QScreen6handleEv at /Users/fons/.julia/conda/3/lib/libQt5Gui.5.9.7.dylib (unknown line)
Allocations: 12180057 (Pool: 12175774; Big: 4283); GC: 11
zsh: segmentation fault julia
```