fix GVPR incorrect interpretation of color strings
The logical operators here were pretty clearly meant to be `&&` not `||`. But
this kind of micro-optimization is unnecessary on modern machines anyway, so we
can just rewrite this into something that is more obvious for both readers and
the compiler.
It would have been nice to add a provoking test case for this as well, but it is
not clear to me how exactly to reach this path. This bug has been open for quite
a while, so it seems simpler to apply the obvious fix and move on.
projects / graphviz / commit