Bug with ax_code_coverage.m4: warning about AM_DISTCHECK_CONFIGURE_FLAGS

Hi,

When using ax_code_coverage.m4 (latest version), I have the following
warning:
-----
Makefile.am:7: warning: AM_DISTCHECK_CONFIGURE_FLAGS was already
defined in condition CODE_COVERAGE_ENABLED, which is included in
condition TRUE ...
    
aminclude_static.am:100: ... 'AM_DISTCHECK_CONFIGURE_FLAGS' previously
defined here

Makefile.am:3:   'aminclude_static.am' included from here
-----

The workaround that I use is to comment/remove the following line from
ax_code_coverage.m4:

A][M_DISTCHECK_CONFIGURE_FLAGS := \$(A][M_DISTCHECK_CONFIGURE_FLAGS) --disable-code-coverage

So, what the *.m4 file is trying to do, is (I suppose), to add
--disable-code-coverage to AM_DISTCHECK_CONFIGURE_FLAGS inside these
conditions:
-----
if CODE_COVERAGE_ENABLED
 ifeq (\$(abs_builddir), \$(abs_top_builddir))
-----

So I manually add --disable-code-coverage in
AM_DISTCHECK_CONFIGURE_FLAGS in the top-level Makefile.am, here is a
simplified version:
-----
# A list of subdirs:
SUBDIRS = [...]

include $(top_srcdir)/aminclude_static.am
clean-local: code-coverage-clean
distclean-local: code-coverage-dist-clean

# Here the real Makefile.am contains other flags.
AM_DISTCHECK_CONFIGURE_FLAGS = --disable-code-coverage
-----

Many thanks for your work in autoconf-archive, by the way.

Best regards,
Sébastien