gnulib-tool.py --create-megatestdir bug

[Bruno Haible]

Hi Collin,

Could you please look at this one? I created a megatestdir for some
portability testing, with gnulib-tool.py (of course), and it failed
on macOS:

Making all in gltests
## ---------------------------------------------------- ##
## ------------------- Gnulib tests ------------------- ##
## You can ignore compiler warnings in this directory.  ##
## ---------------------------------------------------- ##
/Library/Developer/CommandLineTools/usr/bin/make  all-recursive
Making all in .
cc -DHAVE_CONFIG_H -I. -I../../../sys_types/gltests -I..  
-DGNULIB_STRICT_CHECKING=1 -DIN_GNULIB_TESTS=1 -I. -I../../../sys_types/gltests 
-I.. -I../../../sys_types/gltests/.. -I../gllib 
-I../../../sys_types/gltests/../gllib -I/Users/haible/include -Wall  -Wno-error 
-g -O2 -MT test-sys_types.o -MD -MP -MF .deps/test-sys_types.Tpo -c -o 
test-sys_types.o ../../../sys_types/gltests/test-sys_types.c
mv -f .deps/test-sys_types.Tpo .deps/test-sys_types.Po
rm -f libtests.a
ar cr libtests.a
ar: no archive members specified
usage:  ar -d [-TLsv] archive file ...
        ar -m [-TLsv] archive file ...
        ar -m [-abiTLsv] position archive file ...
        ar -p [-TLsv] archive [file ...]
        ar -q [-cTLsv] archive file ...
        ar -r [-cuTLsv] archive file ...
        ar -r [-abciuTLsv] position archive file ...
        ar -t [-TLsv] archive [file ...]
        ar -x [-ouTLsv] archive [file ...]
make[5]: *** [libtests.a] Error 1

The reason appears to be different Makefile.ams generated:

$ rm -rf ../testdir2; GNULIB_TOOL_IMPL=sh+py ./gnulib-tool --create-megatestdir 
--dir=../testdir2 --single-configure sys_types stdio
./gnulib-tool: *** gnulib-tool.py produced different files than gnulib-tool.sh! 
Compare ../testdir2 and ../testdir2-glpy2916071.
./gnulib-tool: *** Stop.

The megatestdir created by the shell implementation builds fine on macOS.

Bruno