Fix bootstrap problem

fix issue introduced with !45 (merged)

The problem is that on sh we were printing the changes to the environment separated by \n, which was fine when passed to eval when the only contained export calls, because they translated to something like:

export A=value export B=value

not beautiful, but working.

With the introduction of source "$LBENV_ALIASES" at the end, we got:

export LBENV_ALIASES=some/path export A=value export B=value source "$LBENV_ALIASES"

which was interpreted as (a single line)

export LBENV_ALIASES=some/path export A=value export B=value source ""

causing the error saying that an empty string is not a valid shell variable name.

Adding a ; to separate the calls to export (as it was already done for csh) fixes the problem.