Docs are being built during 'make check'?

This is weird... Docs are being built during make check. I have to
include MAKEINFO and HELP2MAN in the make check recipe.

My driver scripts looks like:

echo "**********************"
echo "Testing package"
echo "**********************"

MAKE_FLAGS=("check" "V=1" "MAKEINFO=true" "HELP2MAN=true")
if ! "$MAKE" "${MAKE_FLAGS[@]}"
then
    echo "**********************"
    echo "Failed to test Bison"
    echo "**********************"
    exit 1
fi

But the result is:

...
make  check-recursive
make[1]: Entering directory '/home/jwalton/Build-Scripts/bison-3.5.1'
Making check in po
make[2]: Entering directory '/home/jwalton/Build-Scripts/bison-3.5.1/po'
make[2]: Nothing to be done for 'check'.
make[2]: Leaving directory '/home/jwalton/Build-Scripts/bison-3.5.1/po'
Making check in runtime-po
make[2]: Entering directory '/home/jwalton/Build-Scripts/bison-3.5.1/runtime-po'
make[2]: Nothing to be done for 'check'.
make[2]: Leaving directory '/home/jwalton/Build-Scripts/bison-3.5.1/runtime-po'
Making check in gnulib-po
make[2]: Entering directory '/home/jwalton/Build-Scripts/bison-3.5.1/gnulib-po'
make[2]: Nothing to be done for 'check'.
make[2]: Leaving directory '/home/jwalton/Build-Scripts/bison-3.5.1/gnulib-po'
Making check in .
make[2]: Entering directory '/home/jwalton/Build-Scripts/bison-3.5.1'
LC_ALL=C tests/bison --version >doc/bison.help.tmp
LC_ALL=C tests/bison --help | \
  sed -e 's,^Usage: .*/bison \[OPTION\],Usage: bison [OPTION],g' \
      -e '/translation bugs/d'  >>doc/bison.help.tmp
./build-aux/move-if-change doc/bison.help.tmp doc/bison.help
rm -f lib/liby.a
ar cr lib/liby.a lib/main.o lib/yyerror.o
ranlib lib/liby.a
true            \
    --include=./doc/bison.x    \
    --output=doc/bison.1.tmp tests/bison
if sed 's/^\(\.TH[^"]*"[^"]*"[^"]*\)"[^"]*"/\1/' doc/bison.1
>doc/bison.1a.tmp 2>/dev/null &&        \
   sed 's/^\(\.TH[^"]*"[^"]*"[^"]*\)"[^"]*"/\1/' doc/bison.1.tmp | cmp
doc/bison.1a.tmp - >/dev/null 2>&1; then    \
  touch doc/bison.1;                                \
else                                    \
  mv doc/bison.1.tmp doc/bison.1;                        \
fi
sed: can't read doc/bison.1.tmp: No such file or directory
mv: cannot stat 'doc/bison.1.tmp': No such file or directory
Makefile:9562: recipe for target 'doc/bison.1' failed
make[2]: *** [doc/bison.1] Error 1
make[2]: Leaving directory '/home/jwalton/Build-Scripts/bison-3.5.1'
Makefile:8278: recipe for target 'check-recursive' failed
make[1]: *** [check-recursive] Error 1
make[1]: Leaving directory '/home/jwalton/Build-Scripts/bison-3.5.1'
Makefile:8725: recipe for target 'check' failed
make: *** [check] Error 2
**********************
Failed to test Bison
**********************

It is very unusual.