Some related issues at Issue186, Issue664.
Not only push command return 0 exit status on failure
(I use Mercurial 0.9.5 - Release version for Windows.).

Need all command when print
"abort: <abort-reason>"
also return non zero exit status. Firstly for automated script, that used hg
command.

I think this behaviour must be improved and documented.

Changeset 65340b8231eb in crew-stable should fix this.  I'll merge it into
crew later today.

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