It's possible to install scrot with imlib2 without support for any image format. I suppose scrot should require imlib2 to support at least one image format as a sanity check or have the same image use flags and propagate them to imlib or something. Reproducible: Always
Seems to be done since https://gitweb.gentoo.org/repo/gentoo.git/commit/media-gfx/scrot?id=234facb8935dd50a6dc6216e63ff98bc179edf41?