`pin` reports that a picture isn't found when it is there multiple times (instead of reporting it is ambiguous)

[rfindler]

This program:

#lang rhombus
import:
  pict open

def par_bars = square()
def combined = stack(par_bars, par_bars)
def ell = circle()
//Find.center(par_bars).in(combined)
pin(ell,
    ~on: combined,
    ~at: Find.center(par_bars))

produces the error

pin: cannot find pict
  finder: Find()

but par_bars is actually there twice and if you remove the line comment on the call to in, then you'll get the right error:

Find.in: pict location is ambigious
  pict: Pict("square", 21132465)

Also, the finder: line prints the finder just as Find() which seems like it might be a place where there is a straightforward improvement to be had.