mouse not working in 'info'

[Colin Baxter]

I'm using emacs-27.0.50 (build 1, i686-pc-linux-gnu, GTK+ Version
3.14.5) on 3.16.0-5-686-pae #1 SMP Debian 3.16.51-3+deb8u1.

With emacs -q, M-x info RET, if I attempt to use the mouse to go up the
hierarchy of links, i.e., Next: Prev: Up:, I get the errors

<header-line> <header-line> <mouse-2> is undefined
<header-line> <mouse-3> is undefined

if I left- and right-click respectively. I only have a *two* button
mouse. The issue exists only on going up the hierarchy of nodes, not
down. 

Best wishes,