#2597 logcontract and subscripted log

[Barton Willis]

(%i1) logcontract(42+log[x]);
(%o1)                             log(x) + 42

But logcontract(42+a[x]) and ... are correct.

(%i2) build_info();
(%o2)
Maxima version: "branch_5_30_base_98_g29f9239_dirty"
Maxima build date: "2013-06-15 05:29:43"
Host type: "i686-pc-cygwin"
Lisp implementation type: "Clozure Common Lisp"
Lisp implementation version: "Version 1.9-r15764  (WindowsX8632)"

[Rupert Swarbrick]

Fixed in git master by commit 735fb3