diff -r 29e08a98281d -r 0908fbf86e43 Makefile.pre.in
--- a/Makefile.pre.in	Tue May 31 22:31:09 2011 +0200
+++ b/Makefile.pre.in	Tue May 31 23:29:24 2011 +0200
@@ -274,7 +274,7 @@
 
 ASDLGEN_FILES=	$(srcdir)/Parser/asdl.py $(srcdir)/Parser/asdl_c.py
 # XXX Note that a build now requires Python exist before the build starts
-ASDLGEN=	$(srcdir)/Parser/asdl_c.py
+ASDLGEN=	@DISABLE_ASDLGEN@ $(srcdir)/Parser/asdl_c.py
 
 ##########################################################################
 # Python
diff -r 29e08a98281d -r 0908fbf86e43 configure.in
--- a/configure.in	Tue May 31 22:31:09 2011 +0200
+++ b/configure.in	Tue May 31 23:29:24 2011 +0200
@@ -811,7 +811,13 @@
 AC_SUBST(HGVERSION)
 AC_SUBST(HGTAG)
 AC_SUBST(HGBRANCH)
+
+if test -e $srcdir/.hg/00changelog.i
+then
 AC_CHECK_PROG(HAS_HG, hg, found, not-found)
+else
+HAS_HG=no-repository
+fi
 if test $HAS_HG = found
 then
     HGVERSION="hg id -i \$(srcdir)"
@@ -823,6 +829,15 @@
     HGBRANCH=""
 fi
 
+AC_SUBST(DISABLE_ASDLGEN)
+DISABLE_ASDLGEN=""
+AC_CHECK_PROG(HAS_PYTHON, python, found, not-found)
+if test $HAS_HG != found -o $HAS_PYTHON != found
+then
+    DISABLE_ASDLGEN="@echo hg: $HAS_HG, python: $HAS_PYTHON! cannot run \$(srcdir)/Parser/asdl_c.py #"
+fi
+
+
 case $MACHDEP in
 bsdos*|hp*|HP*)
 	# install -d does not work on BSDI or HP-UX