deer: init at 1.4

I wrote the patch. Unfortunately it's Nix specific because upstream
rejected it because Ubuntu Trusty's version of realpath doesn't seem to
have the `--relative-to` option. (Upstream used to use realpath before).
But for Nix, our version of realpath is recent enough. Also, upstream
will probably use realpath again anyway in May 2019 when Ubuntu Trusty
becomes unsupported, so this patch should probably be used.

pkgs/shells/zsh-deer/default.nix

@@ -0,0 +1,36 @@
+{ stdenv, fetchFromGitHub, perl }:
+
+let
+  version = "1.4";
+  name = "deer-${version}";
+in stdenv.mkDerivation {
+  inherit name;
+
+  src = fetchFromGitHub {
+    owner = "Vifon";
+    repo = "deer";
+    rev = "v${version}";
+    sha256 = "1xnbnbi0zk2xsyn8dqsmyxqlfnl36pb1wwibnlp0dxixw6sfymyl";
+  };
+
+  prePatch = ''
+    sed -i '157s/perl/'\
+    "$(echo ${perl}/bin/perl | sed 's/\//\\\//g')"'/' \
+    deer
+  '';
+
+  patches = [ ./realpath.patch ];
+
+  installPhase = ''
+    mkdir -p $out/share/zsh/site-functions/
+    cp deer $out/share/zsh/site-functions/
+  '';
+
+  meta = with stdenv.lib; {
+    description = "Ranger-like file navigation for zsh";
+    homepage = "https://github.com/Vifon/deer";
+    license = licenses.gpl3Plus;
+    maintainers = maintainers.vyp;
+    platforms = platforms.unix;
+  };
+}

pkgs/shells/zsh-deer/realpath.patch

@@ -0,0 +1,28 @@
+From ceadb2f11119143af4f590ea6b05a531483219b5 Mon Sep 17 00:00:00 2001
+From: xd1le <elisp.vim@gmail.com>
+Date: Wed, 30 Aug 2017 17:27:20 +1000
+Subject: [PATCH] use realpath instead of python to calculate relative path
+
+---
+ deer | 5 +----
+ 1 file changed, 1 insertion(+), 4 deletions(-)
+
+diff --git a/deer b/deer
+index 3d89dea..804a871 100644
+--- a/deer
++++ b/deer
+@@ -259,10 +259,7 @@ deer-get-relative()
+ {
+     local TMP
+     TMP=${1:-${DEER_DIRNAME%/}/$DEER_BASENAME[$DEER_DIRNAME]}
+-    TMP="`python -c '
+-import sys, os
+-print(os.path.relpath(sys.argv[1], sys.argv[2]))
+-' $TMP ${DEER_STARTDIR:-$PWD}`"
++    TMP="`realpath --relative-to=${DEER_STARTDIR:-$PWD} $TMP`"
+     print -R $TMP:q
+ }
+ 
+-- 
+2.14.1
+

pkgs/top-level/all-packages.nix

@@ -1597,6 +1597,8 @@ with pkgs;
 
   debootstrap = callPackage ../tools/misc/debootstrap { };
 
+  deer = callPackage ../shells/zsh-deer { };
+
   detox = callPackage ../tools/misc/detox { };
 
   devilspie2 = callPackage ../applications/misc/devilspie2 {