hgtest-push-exit$ hg init r1
hgtest-push-exit$ echo a > r1/a
hgtest-push-exit$ hg -R r1 ci -A -ma
adding a
hgtest-push-exit$ hg clone r1 r2
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
hgtest-push-exit$ echo b > r1/b
hgtest-push-exit$ hg -R r1 ci -A -mb
adding b
hgtest-push-exit$ echo c > r2/c
hgtest-push-exit$ hg -R r2 ci -A -mc
adding c
hgtest-push-exit$ hg -R r2 push r1
pushing to r1
searching for changes
abort: push creates new remote branches!
(did you forget to merge? use push -f to force)
hgtest-push-exit$ echo $?
0