mac build: make a couple of build dependency hints soft imports

the existing environment on otto requires a few build hints in order for
xml parsing to work properly.  these hints are unnecessary, and moreover
their import by depends.py is broken, in the 10.5 environment in which
zandr's buildslave is running.

diff --git a/mac/depends.py b/mac/depends.py
index 6edc850f0796a2885fe3f74ee4f03dba44c05f50..341b41b7f7c441886686824a7ce6eb729c8245f6 100644 (file)
--- a/mac/depends.py
+++ b/mac/depends.py
@@ -10,9 +10,18 @@ from decimal import Decimal
 #if sys.platform in ['darwin', ]:
 from nevow.flat import flatsax
 from xml.parsers import expat
-from xml.sax import expatreader, sax2exts
-from xml.sax.drivers2 import drv_pyexpat, drv_xmlproc
-junk = [ flatsax, expat, expatreader, sax2exts, drv_pyexpat, drv_xmlproc, ]
+from xml.sax import expatreader
+junk = [ flatsax, expat, expatreader, ]
+
+try:
+    # these build hints are needed for nevow/xml on otto's 10.4 / py2.4
+    # environment.  they are broken on zandr's 10.5/py2.5 env, but are
+    # also unnecessary.
+    from xml.sax import sax2exts
+    from xml.sax.drivers2 import drv_pyexpat, drv_xmlproc
+    junk = [ sax2exts, drv_pyexpat, drv_xmlproc, ]
+except:
+    pass