Inconsistent cursors returned for inclusion statements

When retrieving a cursor at a given offset the result is inconsistent when
the offset is within an #include statement
For both below examples I would expect the cursor kind for line 1, column 16
to be CXCursor_InclusionDirective

However,
  clang -lclang -L/usr/lib/llvm -o test test.c

A ./test example1.c 1 16
B ./test example2.c 1 16
C ./test example2.c 2 16

Produces:
A 'string.h' (inclusion directive)
B '' (NoDeclFound)
C 'string.h' (inclusion directive)

Further investigation suggests the exact ordering of the inclusion
directives seems to make a difference and
the inconsistent behaviour affects only the filename and occurs only with
<foo.h> and never with "foo.h"

uname -smr
   Linux 3.11.10-200.fc19.i686.PAE i686
   
clang --version
   clang version 3.3 (tags/RELEASE_33/final)

Any thoughts?

Dave

# example1.c