Puzzling small piece of code - exception block essentially used as goto

[Anonymous Coward <anonymous@coward.org>]

This is an excerpt from some code I recently encountered (it may give
some of you a headache):

  Still_Looping := True;

  Delta_Beyond_Max_Minutes:
    while Still_Looping loop

      Handle_Max_Minute_Error:
        begin

          Hour_Delta    := New_Hour - Hour;
          Still_Looping := False;
          Hour          := New_Hour;

        exception
          when Constraint_Error =>

            if New_Hour > Hour then

              Hour_Delta := Max_Hour_Delta

            else

              Hour_Delta := Relative_Time - Max_Hour_Delta;

            end if;

            Hour := Hour + Hour_Delta;

        end Handle_Max_Minute_Error;
    end loop Delta_Beyond_Max_Minutes;

Tests show that this code actually loops a few times when run in a
typical state.  What I would like clarification on is when the
exception block ends, where is control returned to?

Also, anyone up for the challenge of rewriting this without the
exception handler so the rest of us humans can understand what it's
doing?