Cleanup gittum/slurp syntax

dotfiles/config/gittum/bin/slurp

     #
     # Do the push (if allowed)
     #
-    if $force_push || allowed_push;
-    then
-        if has_flag ci; then
-            git push
-        else
-            git push -o ci.skip
-        fi
+    $force_push || allowed_push || return 0
+    if has_flag ci; then
+        git push
+    else
+        git push -o ci.skip
     fi
 }