New list item is on the same line after undo step

Here are the steps to reproduce:

• type some text, like "abc"
• click the unordered list button from the tool bar
• place the caret in the middle of the list item, like after "a"
• press Tab (4 space are inserted) and then undo
• place the caret at the end of the list item
• press Enter: the newly created list item appears on the same line