[1512] define B10_FROM_BUILD for ddns module tests.

this is the real fix to the distcheck failure on some systems.
in the end LIBRARY_PATH_PLACEHOLDER didn't only unsolve the problem, but
also unnecessary at all.  So the previous change on the makefile was
canceled completely.

configure.ac

@@ -722,7 +722,7 @@ elif test "${log4cplus_path}" != "yes" ; then
   LOG4CPLUS_LIBS="-L${log4cplus_path}/lib"
 else
 # If not specified, try some common paths.
-	log4cplusdirs="/usr/local /usr/pkg /opt /opt/local"
+	log4cplusdirs="/opt/pkg /usr/local /usr/pkg /opt /opt/local"
 	for d in $log4cplusdirs
 	do
 		if test -f $d/include/log4cplus/logger.h; then

src/lib/python/isc/ddns/tests/Makefile.am

@@ -3,17 +3,14 @@ PYTESTS = session_tests.py
 EXTRA_DIST = $(PYTESTS)
 CLEANFILES = $(builddir)/rwtest.sqlite3.copied
 
-# Specify paths to dynamic libraries required by loadable python modules.
-# We at least need to add the path to the data source backend modules.
-# Depending on system details, we may also need to specify the paths to other
-# binding modules.
+# If necessary (rare cases), explicitly specify paths to dynamic libraries
+# required by loadable python modules.
 if SET_ENV_LIBRARY_PATH
 LIBRARY_PATH_PLACEHOLDER = $(ENV_LIBRARY_PATH)=$(abs_top_builddir)/src/lib/cryptolink/.libs:$(abs_top_builddir)/src/lib/dns/.libs:$(abs_top_builddir)/src/lib/dns/python/.libs:$(abs_top_builddir)/src/lib/cc/.libs:$(abs_top_builddir)/src/lib/config/.libs:$(abs_top_builddir)/src/lib/log/.libs:$(abs_top_builddir)/src/lib/util/.libs:$(abs_top_builddir)/src/lib/exceptions/.libs:$(abs_top_builddir)/src/lib/datasrc/.libs:$$$(ENV_LIBRARY_PATH)
-else
-LIBRARY_PATH_PLACEHOLDER = $(ENV_LIBRARY_PATH)=$(abs_top_builddir)/src/lib/datasrc/.libs:$$$(ENV_LIBRARY_PATH)
 endif
 
 # test using command-line arguments, so use check-local target instead of TESTS
+# B10_FROM_BUILD is necessary to load data source backend from the build tree.
 check-local:
 if ENABLE_PYTHON_COVERAGE
 	touch $(abs_top_srcdir)/.coverage
@@ -25,6 +22,7 @@ endif
 	$(LIBRARY_PATH_PLACEHOLDER) \
 	TESTDATA_PATH=$(abs_top_srcdir)/src/lib/testutils/testdata \
 	TESTDATA_WRITE_PATH=$(builddir) \
+	B10_FROM_BUILD=$(abs_top_builddir) \
 	PYTHONPATH=$(COMMON_PYTHON_PATH):$(abs_top_builddir)/src/lib/dns/python/.libs \
 	$(PYCOVERAGE_RUN) $(abs_srcdir)/$$pytest || exit ; \
 	done