nix: fix dogpile imports

pkgs/python-packages-overrides.nix

@@ -21,6 +21,18 b' self: super: {'
     ];
   });
 
+  "dogpile.cache" = super."dogpile.cache".override (attrs: {
+    # dogpile wants to be both a regular module and namespace package
+    postPatch = ''
+      rm dogpile/core.py
+      substituteInPlace dogpile/cache/__init__.py \
+        --replace "from .. import __version__" "__version__ = '0.9.0'"
+      substituteInPlace dogpile/cache/region.py \
+        --replace "from . " "from dogpile.cache " \
+        --replace "from .. " "from dogpile.lock "
+    '';
+  });
+
   "gevent" = super."gevent".override (attrs: {
     propagatedBuildInputs = with self; attrs.propagatedBuildInputs ++ [
       # NOTE: (marcink) odd requirements from gevent aren't set properly,
@@ -43,7 +55,7 b' self: super: {'
       pkgs.apr.dev
       pkgs.aprutil
     ];
-    buildInputs = with self; [
+    buildInputs = with self; attrs.buildInputs ++ [
       pkgs.subversion
     ];
   });