$ groff -p -ms -P -bg -P red -X <<.
.PS
SW: circle "SW"
S:  circle "S"  at SW+(2,0)
SE: circle "SE" at SW+(4,0)
N:  circle "N"  at SW+(2,3.464)
NW: circle "NW" at SW+(1,1.732)
NE: circle "NE" at SW+(3,1.732)
C:  circle "C"  at SW+(2,1.155)
arc chop -> radius 1.155 cw from NW to NE
arc chop -> radius 1.155 cw from NE to S
arc chop -> radius 1.155 cw from S to NW
line chop -> from C to S
.PE
.

has gpic's line beautifully chop outside of the circles but not arc!

My educated guess would be that 2020's gpic is simply lacking code to
calculate the circles' intersection points.

Who wants to add that?

When i try to exercise my software freedoms to inspect and amend the
situation, my trisquel/etiona/ frustrates me with:

$ gdb gpic
GNU gdb (Ubuntu 8.1.1-0ubuntu1) 8.1.1
Copyright (C) 2018 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
[...]
Reading symbols from gpic...(no debugging symbols found)...done.
(gdb) break main
Function "main" not defined.

An open-source system not finding its source!