Refactor slightly.

Author: drewr

git-children-of

@@ -2,9 +2,9 @@
 
 commit=$1
 branch=$2
-if [[ -z "$branch" ]]; then
-    branch=HEAD
-fi
 
-git rev-list --children $branch --not $commit^@ | \
-    awk "/^$commit/ { print \$2 }"
+[ -z "$branch" ] && branch=HEAD
+
+git rev-list --children $branch --not $commit^@ \
+   | awk "/^$commit/ { print \$2 }"
+