Bonds, heretofore issued on any plan, shall not be impaired or disturbed by this act, but until satisfied in full or refunded, bonds shall be entitled to all the support of the law existing at the time the issue was made and of such law as became subsequently available to the support of said issues.
Nor shall this act disturb or impair or invalidate any bond proceedings which have been completed to the point of bond election having been held by the time this act becomes effective.