shell.nix: colorful prompt

https://object.ceph-waw3.hswaw.net/q3k-personal/815968ff10071d4192e464c91b64228e760128267311a94872006d87cbfd0bd9.png

Change-Id: Ia4eeddf045af0d0bdc962087aaeed55d11846648

shell.nix

@@ -12,6 +12,13 @@ in with hscloud.config.pkgs; let
     source ${toString ./.}/env.sh
     ${toString ./.}/tools/install.sh
 
+    # Fancy colorful PS1 to make people notice easily they're in hscloud.
+    PS1='\[\033]0;\u/hscloud:\w\007\]'
+    if type -P dircolors >/dev/null ; then
+      PS1+='\[\033[01;35m\]\u/hscloud\[\033[01;34m\] \w \$\[\033[00m\] '
+    fi
+    export PS1
+
     exec bash "$@"
   '';