Dear Jörg,
thanks for your reply. I totally agree that this is not a severe bug
because a) the Debian build system calls the autoconf tools
automatically and b) a "normal user" can call them manually. The
severity was likely set by the "reportbug" program which I have used for
the first time.
Also, thank you for mentioning the sbuild and pbuilder programs. I will
have a look into both of them.
Still, the xsane source package ships with a xsane.INSTALL documentation
which tells to execute ./configure and a broken configure script. It
might be better to have no configure script at all, or an
xsane.INSTALL.Debian which lists the Debian specific build steps.
But OK, search machines now may find this bug report including the
(manual) solutions, so this might be an acceptable tradeoff.
Thanks for maintaining the xsane program
Johann