postgresql: always create the $out/bin directory

This is needed because some PostgreSQL plugins don't have a bin
directory. If only these plugins are listed in cfg.extraPlugins buildEnv
will turn $out/bin into a symbolic link to ${pg}/bin. Lateron we try to
rm $out/bin/{pg_config,postgres,pg_ctl} which will then fail because
$out/bin will be read-only.

nixos/modules/services/databases/postgresql.nix

@@ -12,10 +12,13 @@ let
     else pkgs.buildEnv {
       name = "postgresql-and-plugins-${(builtins.parseDrvName pg.name).version}";
       paths = [ pg pg.lib ] ++ cfg.extraPlugins;
+      # We include /bin to ensure the $out/bin directory is created which is
+      # needed because we'll be removing files from that directory in postBuild
+      # below. See #22653
+      pathsToLink = [ "/" "/bin" ];
       buildInputs = [ pkgs.makeWrapper ];
       postBuild =
         ''
-          mkdir -p $out/bin
           rm $out/bin/{pg_config,postgres,pg_ctl}
           cp --target-directory=$out/bin ${pg}/bin/{postgres,pg_config,pg_ctl}
           wrapProgram $out/bin/postgres --set NIX_PGLIBDIR $out/lib

pkgs/servers/sql/postgresql/ext/pg_cron.nix

@@ -14,7 +14,6 @@ stdenv.mkDerivation rec {
   };
 
   installPhase = ''
-    mkdir -p $out/bin    # For buildEnv to setup proper symlinks. See #22653
     mkdir -p $out/{lib,share/extension}
 
     cp *.so      $out/lib

pkgs/servers/sql/postgresql/ext/pg_similarity.nix

@@ -13,7 +13,6 @@ stdenv.mkDerivation {
   buildInputs = [ postgresql gcc ];
   buildPhase = "USE_PGXS=1 make";
   installPhase = ''
-    mkdir -p $out/bin   # for buildEnv to setup proper symlinks
     install -D pg_similarity.so -t $out/lib/
     install -D ./{pg_similarity--unpackaged--1.0.sql,pg_similarity--1.0.sql,pg_similarity.control} -t $out/share/extension
   '';

pkgs/servers/sql/postgresql/ext/pgjwt.nix

@@ -13,7 +13,6 @@ stdenv.mkDerivation rec {
 
   buildPhase = ":";
   installPhase = ''
-    mkdir -p $out/bin  # current postgresql extension mechanism in nixos requires bin directory
     mkdir -p $out/share/extension
     cp pg*sql *.control $out/share/extension
   '';

pkgs/servers/sql/postgresql/ext/pgroonga.nix

@@ -15,7 +15,6 @@ stdenv.mkDerivation rec {
   makeFlags = [ "HAVE_MSGPACK=1" ];
 
   installPhase = ''
-    mkdir -p $out/bin
     install -D pgroonga.so -t $out/lib/
     install -D ./{pgroonga-*.sql,pgroonga.control} -t $out/share/extension
   '';

pkgs/servers/sql/postgresql/ext/pgrouting.nix

@@ -15,7 +15,6 @@ stdenv.mkDerivation rec {
   };
 
   installPhase = ''
-    mkdir -p $out/bin # for buildEnv, see https://github.com/NixOS/nixpkgs/issues/22653
     install -D lib/*.so                        -t $out/lib
     install -D sql/pgrouting--${version}.sql   -t $out/share/extension
     install -D sql/common/pgrouting.control    -t $out/share/extension

pkgs/servers/sql/postgresql/ext/plv8.nix

@@ -23,7 +23,6 @@ stdenv.mkDerivation rec {
   buildPhase = "make -f Makefile.shared all";
 
   installPhase = ''
-    mkdir -p $out/bin
     install -D plv8*.so                                        -t $out/lib
     install -D {plls,plcoffee,plv8}{--${version}.sql,.control} -t $out/share/extension
   '';

pkgs/servers/sql/postgresql/ext/timescaledb.nix

@@ -34,13 +34,6 @@ stdenv.mkDerivation rec {
     done
   '';
 
-  postInstall = ''
-    # work around an annoying bug, by creating $out/bin, so buildEnv doesn't freak out later
-    # see https://github.com/NixOS/nixpkgs/issues/22653
-
-    mkdir -p $out/bin
-  '';
-
   meta = with stdenv.lib; {
     description = "Scales PostgreSQL for time-series data via automatic partitioning across time and space";
     homepage    = https://www.timescale.com/;

pkgs/servers/sql/postgresql/ext/tsearch_extras.nix

@@ -15,7 +15,6 @@ stdenv.mkDerivation rec {
   buildInputs = [ postgresql ];
 
   installPhase = ''
-    mkdir -p $out/bin
     install -D tsearch_extras.so -t $out/lib/
     install -D ./{tsearch_extras--1.0.sql,tsearch_extras.control} -t $out/share/extension
   '';