When identical changes are made on separate branches, the manifest for the
second commit will reuse the filelog entry for the first.

When you then specify a file (instead of a pattern) for hg log, the second
changeset will incorrectly fail to appear in hg log output.  For the same file,
specified as a pattern, both changesets will appear correctly.

Example:

% hg log -l 4 --template '{rev}\t' usr/src/uts/intel/ip/ip.global-objs.debug64 ;
echo 
8037	8023	7749	7502	
%	hg log -l 4 --template '{rev}\t' -I
usr/src/uts/intel/ip/ip.global-objs.debug64 ; echo
8037	8032	8023	7749	
%	

This problem showed up in the same workspace as issue 1327, and (like 1327, I
believe) stems from reuse of identical filelog entries.