Weird compilation bug just started appearing

[Lars Ingebrigtsen]

I'm getting:

make[2]: Entering directory '/home/larsi/src/emacs/trunk/lisp'
  ELC      auth-source.elc

In toplevel form:
auth-source.el:42:1:Error: Wrong type argument: symbolp, 2.0
Makefile:296: recipe for target 'auth-source.elc' failed
make[2]: *** [auth-source.elc] Error 1
make[2]: Leaving directory '/home/larsi/src/emacs/trunk/lisp'
Makefile:319: recipe for target 'compile-main' failed
make[1]: *** [compile-main] Error 2
make[1]: Leaving directory '/home/larsi/src/emacs/trunk/lisp'
Makefile:411: recipe for target 'lisp' failed
make: *** [lisp] Error 2

This is after a fresh checkout...  but I'm only getting it on one
laptop -- the other machine's tree is fine.

And both trees are fresh checkouts.  Both machines are Debian 9
machines.

I must have borked something up somewhere...  or is anybody else also
seeing this?

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no