2.10.0 has breaking changes to isBefore and isAfter with empty dates

[stijnherreman]

After upgrading from 2.8.2 to 2.12.0, I noticed breaking changes to isBefore and isAfter in 2.10.0 and one ore more versions between 2.10.0 and 2.12.0

Test case on Firefox 44.0.2:

var emptyDateIsBeforeDateInThePast = moment("", "DD-MM-YYYY").isBefore(moment("2016-01-01"));
var emptyDateIsBeforeToday = moment("", "DD-MM-YYYY").isBefore(moment("2016-03-16"));
var emptyDateIsBeforeDateInTheFuture = moment("", "DD-MM-YYYY").isBefore(moment("2016-12-31"));
var emptyDateIsAfterDateInThePast = moment("", "DD-MM-YYYY").isAfter(moment("2016-01-01"));
var emptyDateIsAfterToday = moment("", "DD-MM-YYYY").isAfter(moment("2016-03-16"));
var emptyDateIsAfterDateInTheFuture = moment("", "DD-MM-YYYY").isAfter(moment("2016-12-31"));

console.log("emptyDateIsBeforeDateInThePast", emptyDateIsBeforeDateInThePast);
console.log("emptyDateIsBeforeToday", emptyDateIsBeforeToday);
console.log("emptyDateIsBeforeDateInTheFuture", emptyDateIsBeforeDateInTheFuture);
console.log("emptyDateIsAfterDateInThePast", emptyDateIsAfterDateInThePast);
console.log("emptyDateIsAfterToday", emptyDateIsAfterToday);
console.log("emptyDateIsAfterDateInTheFuture", emptyDateIsAfterDateInTheFuture);

Output on 2.8.2:

emptyDateIsBeforeDateInThePast true
emptyDateIsBeforeToday true
emptyDateIsBeforeDateInTheFuture true
emptyDateIsAfterDateInThePast false
emptyDateIsAfterToday false
emptyDateIsAfterDateInTheFuture false

Output on 2.9.0:

emptyDateIsBeforeDateInThePast true
emptyDateIsBeforeToday true
emptyDateIsBeforeDateInTheFuture true
emptyDateIsAfterDateInThePast false
emptyDateIsAfterToday false
emptyDateIsAfterDateInTheFuture false

Output on 2.10.0

emptyDateIsBeforeDateInThePast false
emptyDateIsBeforeToday false
emptyDateIsBeforeDateInTheFuture true
emptyDateIsAfterDateInThePast true
emptyDateIsAfterToday false
emptyDateIsAfterDateInTheFuture false

Output on 2.12.0

emptyDateIsBeforeDateInThePast false
emptyDateIsBeforeToday false
emptyDateIsBeforeDateInTheFuture false
emptyDateIsAfterDateInThePast false
emptyDateIsAfterToday false
emptyDateIsAfterDateInTheFuture false

2.10.0 immediately follows 2.9.0, and this is the changelog for 2.10.0:

Ported code to es6 modules

It's a little late to do anything about this now, and I'll adapt the broken code to work properly with the latest version. However, I do not understand how there can be any functional change at all in 2.10.0

I think a warning in the changelog would be useful, to indicate that even though it's supposed to be refactoring only, there are an unknown number of breaking changes.

[mattjohnsonpint]

Comparison of invalid moments was an edge case that had not been tested properly in previous releases. There was no behavioral contract that "" was either greater than or less than or equal to some other valid moment or some other invalid moment. There were multiple bugs reported on this, and we fixed them. I don't consider this a breaking change.

See #2624, #2619, #2438, #2370, #2462, #2354, #2819, and I'm sure there are a few more.
The changelog does indeed call this out in versions 2.10.5 (#2438 Fix inconsistent moment.min and moment.max results) and 2.11.0 (#2624 Proper handling of invalid moments).