Commented Issue: MaskedEditExtender fails when MaskType="DateTime" and AcceptAMPM="false" [26785]

When using the ajax toolkit version 3.5.40412.2, MaskType="DateTime" and AcceptAMPM="false" (or UserTimeFormat="TwentyFourHour"), MaskedEditExtender does not allow the time to be set. When the textbox loses focus the hour and minute are set to the two digit month and two digit day used in the date portion.

I read a post which said Reverting MaskedEditBehavior.pre.js back to 2178bc382e94 fixes the problem.
What does this mean please Explain in detail as i am new Ajax
Comments: The same problem on 4.1.51116.0