bash appears to have bug in the handling of the last line in a script.
If the last line invokes an executable, the script exits with bad return
value regardless of the return value of the executable.
to invoke, create two files,

foo:
---------cut here---------
#a script
/bin/echo hithere
---------cut here---------

bar:
---------cut here---------
#a script
/bin/echo hithere

---------cut here---------

then from a shell run
bash -c ". foo; echo done"
bash -c ". bar; echo done"

In the first case you will get
hithere

In the second case you will get
hithere
done


bash2, zsh, etc., will always give you the second case.
b.c.