kicad: avoid rebuild on date change

the date changes more often than most of the inputs
the date can also change on the base without other changes
  this causes a substantial rebuild for no reason

pkgs/applications/science/electronics/kicad/base.nix

@@ -61,7 +61,7 @@ let
 in
 stdenv.mkDerivation rec {
   pname = "kicad-base";
-  version = kicadVersion;
+  version = if (stable) then kicadVersion else builtins.substring 0 10 src.rev;
 
   src = kicadSrc;
 

pkgs/applications/science/electronics/kicad/default.nix

@@ -155,11 +155,8 @@ in
 stdenv.mkDerivation rec {
 
   # Common libraries, referenced during runtime, via the wrapper.
-  passthru.libraries = callPackages ./libraries.nix { inherit libSrc libVersion; };
-  passthru.i18n = callPackage ./i18n.nix {
-    src = i18nSrc;
-    version = i18nVersion;
-  };
+  passthru.libraries = callPackages ./libraries.nix { inherit libSrc; };
+  passthru.i18n = callPackage ./i18n.nix { src = i18nSrc; };
   base = callPackage ./base.nix {
     inherit stable baseName;
     inherit kicadSrc kicadVersion;
@@ -169,7 +166,7 @@ stdenv.mkDerivation rec {
   };
 
   inherit pname;
-  version = kicadVersion;
+  version = if (stable) then kicadVersion else builtins.substring 0 10 src.src.rev;
 
   src = base;
   dontUnpack = true;

pkgs/applications/science/electronics/kicad/i18n.nix

@@ -2,13 +2,13 @@
 , cmake
 , gettext
 , src
-, version
 }:
 
 stdenv.mkDerivation {
-  inherit src version;
+  inherit src;
 
   pname = "kicad-i18n";
+  version = builtins.substring 0 10 src.rev;
 
   nativeBuildInputs = [ cmake gettext ];
   meta = with lib; {

pkgs/applications/science/electronics/kicad/libraries.nix

@@ -2,13 +2,12 @@
 , cmake
 , gettext
 , libSrc
-, libVersion
 }:
 let
   mkLib = name:
     stdenv.mkDerivation {
       pname = "kicad-${name}";
-      version = libVersion;
+      version = builtins.substring 0 10 (libSrc name).rev;
 
       src = libSrc name;