The end of the make log goes:
test -z ""Hello, GNU World"" \
&& { echo define manual_title in
cfg.mk 1>&2; exit 1; } || :
/bin/bash: line 0: test: too many arguments
cd './doc'; \
/bin/bash ../build-aux/gendocs.sh \
-o '/home/rrt/repo/hello/doc/manual' \
--email
address@hidden hello \
"GNU Hello - "Hello, GNU World""
../build-aux/gendocs.sh: extra non-option argument `GNU'.
make[1]: *** [web-manual] Error 1
make[1]: Leaving directory `/home/rrt/repo/hello'
Switched to branch 'master'
Deleted branch web-doc-2.9-10885 (was 65dc2fd).
make: *** [web-manual-update] Error 2
AC_INIT does indeed have a first argument of "GNU hello", but other projects (e.g. coreutils) do similarly.