Fish: vv for Python venvs

vv searches for and activates the nearest directory named "venv" in the
current directory upward (stopping if it finds a .git).

fish/functions/vv.fish

@@ -1,5 +1,29 @@
 #!/usr/bin/env fish
 
 function vv
-    source venv/bin/activate.fish
+    pushd . &> /dev/null
+    function find_root
+        set -l dir $PWD
+
+        if test -d $dir/venv
+            echo $dir
+            return 0
+        end
+
+        if test -d .git -o "$dir" = "/"
+            return 1
+        end
+
+        cd ..
+        find_root
+    end
+
+    if not find_root &> /dev/null
+        echo "Couldn't find venv"
+        popd &> /dev/null
+        return 1
+    end
+
+    source (find_root)/venv/bin/activate.fish
+    popd &> /dev/null
 end