use $(abs_srcdir) instead of hardcoded path to test data to make it

distcheck friendly.
this may be a bit non trivial, but I'mgoing to push without a review
as this has been causing buildbot errors.

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

@@ -15,5 +15,6 @@ endif
 	for pytest in $(PYTESTS) ; do \
 	echo Running test: $$pytest ; \
 	env PYTHONPATH=$(abs_top_srcdir)/src/lib/python:$(abs_top_builddir)/src/lib/python:$(abs_top_builddir)/src/lib/python/isc/log \
+	TESTDATA_PATH=$(abs_srcdir)/testdata \
 	$(PYCOVERAGE_RUN) $(abs_srcdir)/$$pytest || exit ; \
 	done

src/lib/python/isc/datasrc/tests/sqlite3_ds_test.py

@@ -14,10 +14,11 @@
 # WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 
 from isc.datasrc import sqlite3_ds
+import os
 import socket
 import unittest
 
-TEST_DATA_PATH = "./testdata/"
+TESTDATA_PATH = os.environ['TESTDATA_PATH'] + os.sep
 
 class TestSqlite3_ds(unittest.TestCase):
     def test_zone_exist(self):
@@ -32,11 +33,11 @@ class TestSqlite3_ds(unittest.TestCase):
         # Open a broken database file
         self.assertRaises(sqlite3_ds.Sqlite3DSError,
                           sqlite3_ds.zone_exist, "example.com",
-                          TEST_DATA_PATH + "brokendb.sqlite3")
+                          TESTDATA_PATH + "brokendb.sqlite3")
         self.assertTrue(sqlite3_ds.zone_exist("example.com.",
-                            TEST_DATA_PATH + "example.com.sqlite3"))
+                            TESTDATA_PATH + "example.com.sqlite3"))
         self.assertFalse(sqlite3_ds.zone_exist("example.org.",
-                            TEST_DATA_PATH + "example.com.sqlite3"))
+                            TESTDATA_PATH + "example.com.sqlite3"))
 
 if __name__ == '__main__':
     unittest.main()