should die informatively when there is no png for an organism tree
tree4835ca23d4c87923f1173dcaf59dc23f0c2bee8a
-rw-r--r-- 167 .gitignore
-rw-r--r-- 14189 Build.PL
-rw-r--r-- 101 Changes
drwxr-xr-x - bin
drwxr-xr-x - cgi-bin
drwxr-xr-x - conf
drwxr-xr-x - db
lrwxrwxrwx 17 documents -> static/documents/
drwxr-xr-x - features
drwxr-xr-x - js
drwxr-xr-x - lib
drwxr-xr-x - mason
drwxr-xr-x - programs
drwxr-xr-x - selenium
drwxr-xr-x - static
drwxr-xr-x - support_data
drwxr-xr-x - t