beaker: add patch for metadata re-use

pkgs/patch-beaker-metadata-reuse.diff

@@ -0,0 +1,13 b''
+diff -rup Beaker-1.9.1-orig/beaker/ext/database.py Beaker-1.9.1/beaker/ext/database.py
+--- Beaker-1.9.1-orig/beaker/ext/database.py	2018-05-22 18:22:34.802619619 +0200
++++ Beaker-1.9.1/beaker/ext/database.py	2018-05-22 17:07:14.048335196 +0200
+@@ -91,7 +91,8 @@ class DatabaseNamespaceManager(OpenResou
+                              sa.Column('created', types.DateTime, nullable=False),
+                              sa.Column('data', types.PickleType, nullable=False),
+                              sa.UniqueConstraint('namespace'),
+-                             schema=schema_name if schema_name else meta.schema
++                             schema=schema_name if schema_name else meta.schema,
++                             extend_existing=True
+             )
+             cache.create(checkfirst=True)
+             return cache

pkgs/python-packages-overrides.nix

@@ -1,60 +1,61 b''
 # Overrides for the generated python-packages.nix
 #
 # This function is intended to be used as an extension to the generated file
 # python-packages.nix. The main objective is to add needed dependencies of C
 # libraries and tweak the build instructions where needed.
 
 { pkgs, basePythonPackages }:
 
 let
   sed = "sed -i";
 in
 
 self: super: {
 
   beaker = super.beaker.override (attrs: {
     patches = [
       ./patch-beaker-lock-func-debug.diff
+      ./patch-beaker-metadata-reuse.diff
     ];
   });
 
   subvertpy = super.subvertpy.override (attrs: {
     # TODO: johbo: Remove the "or" once we drop 16.03 support
     SVN_PREFIX = "${pkgs.subversion.dev or pkgs.subversion}";
     propagatedBuildInputs = attrs.propagatedBuildInputs ++ [
       pkgs.aprutil
       pkgs.subversion
     ];
     preBuild = pkgs.lib.optionalString pkgs.stdenv.isDarwin ''
       ${sed} -e "s/'gcc'/'clang'/" setup.py
     '';
   });
 
   hgsubversion = super.hgsubversion.override (attrs: {
     propagatedBuildInputs = attrs.propagatedBuildInputs ++ [
       pkgs.sqlite
       basePythonPackages.sqlite3
     ];
   });
 
   mercurial = super.mercurial.override (attrs: {
     propagatedBuildInputs = attrs.propagatedBuildInputs ++ [
       self.python.modules.curses
     ] ++ pkgs.lib.optional pkgs.stdenv.isDarwin
       pkgs.darwin.apple_sdk.frameworks.ApplicationServices;
   });
 
   pyramid = super.pyramid.override (attrs: {
     postFixup = ''
       wrapPythonPrograms
       # TODO: johbo: "wrapPython" adds this magic line which
       # confuses pserve.
       ${sed} '/import sys; sys.argv/d' $out/bin/.pserve-wrapped
     '';
   });
 
   # Avoid that setuptools is replaced, this leads to trouble
   # with buildPythonPackage.
   setuptools = basePythonPackages.setuptools;
 
 }