stephen@bb:~/src/texmacs-2.0$ ./configure --enable-guile2
checking build system type... x86_64-pc-linux-gnu
checking host system type... x86_64-pc-linux-gnu
checking current Subversion revision number... 10846
checking for gcc... gcc
checking whether the C compiler works... yes
checking for C compiler default output file name... a.out
checking for suffix of executables...
checking whether we are cross compiling... no
checking for suffix of object files... o
checking whether we are using the GNU C compiler... yes
checking whether gcc accepts -g... yes
checking for gcc option to accept ISO C89... none needed
checking for g++... g++
checking whether we are using the GNU C++ compiler... yes
checking whether g++ accepts -g... yes
checking for clang... no
checking for gcc... gcc
checking whether we are using the GNU Objective C compiler... no
checking whether gcc accepts -g... no
checking for clang++... no
checking for g++... g++
checking whether we are using the GNU Objective C++ compiler... no
checking whether g++ accepts -g... no
checking whether GNU C++ compiler is default... yes
checking version of gcc... 6.3.0
checking version of g++... 6.3.0
checking for C++ stack backtrace support... yes
checking how to run the C++ preprocessor... g++ -E
checking for grep that handles long lines and -e... /bin/grep
checking for egrep... /bin/grep -E
checking for ANSI C header files... yes
checking for sys/types.h... yes
checking for sys/stat.h... yes
checking for stdlib.h... yes
checking for string.h... yes
checking for memory.h... yes
checking for strings.h... yes
checking for inttypes.h... yes
checking for stdint.h... yes
checking for unistd.h... yes
checking for FILE... yes
checking for intptr_t... yes
checking for time_t... yes
checking pty.h usability... yes
checking pty.h presence... yes
checking for pty.h... yes
checking util.h usability... no
checking util.h presence... no
checking for util.h... no
checking for gettimeofday... yes
checking size of void *... 8
checking if we are on a 64-bits computer... yes
final adjustments for an Intel or AMD GNU/Linux host
checking for XML_ParserCreate in -lexpat... yes
checking for xcb_disconnect in -lxcb... yes
checking for guile18-config... no
checking for guile1.8-config... no
checking for guile16-config... no
checking for guile1.6-config... no
checking for guile1-config... no
checking for guile-config... guile-config
checking whether C++ compiler accepts -pthread... yes
configure: Guile version 2.0
configure: error: TeXmacs is incompatible with Guile 2.
    If you know what you are doing, run configure with --enable-guile2