If you copy a file and modify the copy, 'hg log --stat' will incorrectly report that the original was modified instead of the copy.

A reproduction:

    $ hg init test
    $ cd test
    $ echo "a\nb\nc" > a
    $ hg add a
    $ hg commit -m a
    $ hg cp a b
    $ echo d >> b
    $ hg commit -m b
    $ hg --config diff.git=true log -r . --stat 
    changeset:   1:4f4a6de064c5
    tag:         tip
    user:        Michael O'Connor <moconnor@janestreet.com>
    date:        Wed Apr 09 23:08:08 2014 -0400
    summary:     b
    
     a |  1 +
     1 files changed, 1 insertions(+), 0 deletions(-)

Note that (at least my version of) diffstat gets this case right:

    $ hg --config diff.git=true log -r . -p | diffstat
     b |    1 +
     1 file changed, 1 insertion(+)
    $ diffstat --version
    diffstat version 1.51

Also, with a move instead of a copy+modification, what --stat reports seems at least strange to me:

    $ hg update 0
    0 files updated, 0 files merged, 1 files removed, 0 files unresolved
    $ hg mv a b
    $ hg commit -m 'mv a b'
    created new head
    $ hg --config diff.git=true log -r . --stat
    changeset:   2:15831134b1bb
    tag:         tip
    parent:      0:e096287bb74a
    user:        Michael O'Connor <moconnor@janestreet.com>
    date:        Wed Apr 09 23:15:32 2014 -0400
    summary:     mv a b
    
     a |  0 
     1 files changed, 0 insertions(+), 0 deletions(-)

Thanks!