Guile problem building 2.6.3 from git on Ubuntu 12.04

[Colin Law]

Building from the tag 2.6.3 in git on Ubuntu 12.04 I have this error
during configure

checking for guile-1.8 >= 1.8.5... yes
checking GUILE_CFLAGS... -pthread
checking GUILE_LIBS... -Wl,-Bsymbolic-functions -lguile -lgmp -lcrypt -lm -lltdl
../configure: line 20528: syntax error near unexpected token
`gnc_have_guile_www,'
../configure: line 20528: `
GUILE_MODULE_AVAILABLE(gnc_have_guile_www,(www main))'

I have guile-1.8, guile-1.8-dev and swig installed.
Google suggested that this could be caused by
/usr/share/aclocal/guile.m4 not being found, but this file is present.

Cheers

Colin