bootstraping letor error

Bootstrapping `xapian-letor'
libtoolize: putting auxiliary files in '.'.
libtoolize: copying file './ltmain.sh'
libtoolize: putting macros in AC_CONFIG_MACRO_DIRS, 'm4'.
libtoolize: copying file 'm4/libtool.m4'
libtoolize: copying file 'm4/ltoptions.m4'
libtoolize: copying file 'm4/ltsugar.m4'
libtoolize: copying file 'm4/ltversion.m4'
libtoolize: copying file 'm4/lt~obsolete.m4'
Unescaped left brace in regex is deprecated, passed through in regex; marked by <-- HERE in m/\${ <-- HERE ([^ \t=:+{}]+)}/ at /home/ayush/Desktop/xapian-patch/xapian/INST/bin/automake line 3936.
configure.ac:50: installing './compile'
configure.ac:41: installing './missing'
Makefile.am: installing './INSTALL'
Makefile.am: installing './depcomp'
tests/Makefile.am:24: error: BUILD_BACKEND_REMOTE does not appear in AM_CONDITIONAL
tests/Makefile.am:33: error: BUILD_BACKEND_GLASS does not appear in AM_CONDITIONAL
tests/Makefile.am:42: error: BUILD_BACKEND_GLASS does not appear in AM_CONDITIONAL
tests/harness/Makefile.mk:44: error: BUILD_BACKEND_GLASS does not appear in AM_CONDITIONAL
tests/Makefile.am:123:   'tests/harness/Makefile.mk' included from here
tests/harness/Makefile.mk:50: error: BUILD_BACKEND_INMEMORY does not appear in AM_CONDITIONAL
tests/Makefile.am:123:   'tests/harness/Makefile.mk' included from here
tests/harness/Makefile.mk:54: error: BUILD_BACKEND_REMOTE does not appear in AM_CONDITIONAL
tests/Makefile.am:123:   'tests/harness/Makefile.mk' included from here
autoreconf: /home/ayush/Desktop/xapian-patch/xapian/INST/bin/automake failed with exit status: 1
Bootstrap failed