home: git: add 'pick' alias

I wanted to name it 'pickaxe' but for a curious reason, it does not seem
to be working when I use that alias...

I am trying to find a second alias name for `git log -p -S`, which only
shows commits that change the number of occurrences of its pickaxe in
the file. Whereas `-G` shows any commit involving the pickaxe in its
diff.

home/git/default.nix

@@ -23,6 +23,7 @@ in
       assume = "update-index --assume-unchanged";
       unassume = "update-index --no-assume-unchanged";
       assumed = "!git ls-files -v | grep ^h | cut -c 3-";
+      pick = "log -p -G";
       push-new = "!git push -u origin "
         + ''"$(git branch | grep '^* ' | cut -f2- -d' ')"'';
     };