in
https://bugzilla.opensuse.org/show_bug.cgi?id=1021353

we found that calling two autogen processes in parallel in the same directory (e.g. through make -j2) can cause the output to be silently corrupted
e.g. usually one of the outputs is missing and the remaining might contain the content of the other one.
In addition no error is returned by autogen in that case.

to reproduce with the attached tarball do

tar xf autogenracetest.tar.gz
cd autogenracetest/outdir/
../test.sh
# or
make clean ; make -j2 all

while this will always work fine:
make clean ; make all

The underlying problem is that both create a "args.man"
temporary file stepping on each others toes
and not even notice