libxml2: bump 2.9.0 -> 2.9.1 (CVE-2013-1969)

And drop patch that has been merged upstream.
Close #1199.
Hack around python install problems (the rest is from bjornfor).

pkgs/development/libraries/libxml2/default.nix

@@ -2,20 +2,17 @@
 
 assert pythonSupport -> python != null;
 
-stdenv.mkDerivation rec {
-  name = "libxml2-2.9.0";
+#TODO: share most stuff between python and non-python builds, perhaps via multiple-output
+
+stdenv.mkDerivation (rec {
+  name = "libxml2-2.9.1";
 
   src = fetchurl {
     url = "ftp://xmlsoft.org/libxml2/${name}.tar.gz";
-    sha256 = "10ib8bpar2pl68aqksfinvfmqknwnk7i35ibq6yjl8dpb0cxj9dd";
+    sha256 = "1nqgd1qqmg0cg09mch78m2ac9klj9n87blilx4kymi7jcv5n8g7x";
   };
 
-  patches = [ ./pthread-once-init.patch ];
-
-  configureFlags = stdenv.lib.optionalString pythonSupport "--with-python=${python}";
-
-  buildInputs = (stdenv.lib.optional pythonSupport [ python ])
-
+  buildInputs = stdenv.lib.optional pythonSupport python
     # Libxml2 has an optional dependency on liblzma.  However, on impure
     # platforms, it may end up using that from /usr/lib, and thus lack a
     # RUNPATH for that, leading to undefined references for its users.
@@ -36,4 +33,12 @@ stdenv.mkDerivation rec {
     platforms = stdenv.lib.platforms.unix;
     maintainers = [ stdenv.lib.maintainers.eelco ];
   };
-}
+
+} // stdenv.lib.optionalAttrs pythonSupport {
+  configureFlags = "--with-python=${python}";
+
+  # this is a pair of ugly hacks to make python stuff install into the right place
+  preInstall = ''substituteInPlace python/libxml2mod.la --replace "${python}" "$out"'';
+  installFlags = ''pythondir="$(out)/lib/${python.libPrefix}/site-packages"'';
+})
+