bfastts: error if time series contains leap day

[GreatEmerald]

If we have the leap day (Feb 29) and also the day after (March 1) in the time series, bfastts fails with an error:

Error in merge.zoo(zoo(coredata(x), tt), zoo(, tt2)) : 
  series cannot be merged with non-unique index entries in a series
In addition: Warning messages:
1: In zoo(data, 1900 + as.POSIXlt(dates)$year + (yday365(dates) - 1)/365,  :
  some methods for “zoo” objects do not work if the index entries in ‘order.by’ are not unique

MWE:
Fails:

a = c(as.Date("2016-02-29"), as.Date("2016-03-01"))
b = 1:2
bfastts(b, a, type="irregular")

Works if we set it to be one day later:

a = c(as.Date("2016-02-29"), as.Date("2016-03-01"))
b = 1:2
bfastts(b, a+1, type="irregular")