This patch is against emacs 2.32 in Fedora 14, but the relevant regexp 
seems to be unchanged in the current source tree.

When I do C-x 4 a in a ChangeLog file, it creates an empty item that 
looks like

	*

If I then switch to another source file in the same directory and do C-x 
4 a again, I get

	*
myfile.c (somefn):

rather than

	* myfile.c (somefn):

This is due to the regular expression used to search for an empty item 
in add-change-log-entry.  "^\\s *\\*\\s *$" looks for any whitespace 
followed by a *, followed by any whitespace, followed by the end of a 
line.  Unfortunately, when faced with

	*

this regexp matches not only the line with the * on it, but the newline 
at the end, and the $ matches the end of the following empty line.

My patch changes the final "\\s *" to just " *" so it doesn't match 
newlines.