BUG: densify and daylight saving

Working with Data
#1

If I apply the densify function using day or month as a range unit on a period that contains daylight saving adjustment, Mongo returns to me sample with ugly dates, because it is not able to apply timezone with the densify step.

Example, if I have 2 samples like this (base location is Europe/Rome):

{
    "ts" : ISODate("2000-12-31T23:00:00.000+0000"),
    "meta" : {
        "device" : "custom",
        "series" : "custom:1"
    },
    "v" : 100.84432598221046
}
{
    "ts" : ISODate("2001-06-30T22:00:00.000+0000"),
    "meta" : {
        "device" : "custom",
        "series" : "custom:1"
    },
    "v" : 100.14378032120374,
}

when I apply densify the result is:

{
    "ts" : ISODate("2000-12-31T23:00:00.000+0000"),
    "meta" : {
        "device" : "custom",
        "series" : "custom:1"
    },
    "v" : 100.84432598221046
}
{
    "ts" : ISODate("2001-01-31T23:00:00.000+0000")
}
{
    "ts" : ISODate("2001-02-28T23:00:00.000+0000")
}
{
    "ts" : ISODate("2001-03-28T23:00:00.000+0000")
}
{
    "ts" : ISODate("2001-04-28T23:00:00.000+0000")
}
{
    "ts" : ISODate("2001-05-28T23:00:00.000+0000")
}
{
    "ts" : ISODate("2001-06-28T23:00:00.000+0000")
}
{
    "ts" : ISODate("2001-06-30T22:00:00.000+0000"),
    "meta" : {
        "device" : "custom",
        "series" : "custom:1"
    },
    "v" : 100.14378032120374,
}

you can see it starts to use day 28!!!

If I have samples like this:

{
    "ts" : ISODate("2001-01-31T23:00:00.000+0000"),
    "meta" : {
        "device" : "custom",
        "series" : "custom:1"
    },
    "v" : 100.50917810392826,
}
{
    "ts" : ISODate("2001-02-28T23:00:00.000+0000"),
    "meta" : {
        "device" : "custom",
        "series" : "custom:1"
    },
    "v" : 100.84507500021624,
}
{
    "ts" : ISODate("2001-03-31T22:00:00.000+0000"),
    "meta" : {
        "device" : "custom",
        "series" : "custom:1"
    },
    "v" : 100.51826982331077,
}

and I apply densify, the result is:

{
    "ts" : ISODate("2001-01-31T23:00:00.000+0000"),
    "meta" : {
        "device" : "custom",
        "series" : "custom:1"
    },
    "v" : 100.50917810392826,
}
{
    "ts" : ISODate("2001-02-28T23:00:00.000+0000"),
    "meta" : {
        "device" : "custom",
        "series" : "custom:1"
    },
    "v" : 100.84507500021624,
}
{
    "ts" : ISODate("2001-03-28T23:00:00.000+0000")
}
{
    "ts" : ISODate("2001-03-31T22:00:00.000+0000"),
    "meta" : {
        "device" : "custom",
        "series" : "custom:1"
    },
    "v" : 100.51826982331077,
}

you can see Mongo creates a document that is not usefull