add_TA legend argument cannot be set

[helgasoft]

Description

I appears the legend argument of add_TA cannot be changed from default 'auto' to a custom string.

Expected behavior

I hoped add_TA would work like the standard function addTA.

Minimal, reproducible example

getSymbols('T')
chartSeries(T); addTA(EMA(Cl(T)), legend="myEMA")	# does it ok
chart_Series(T); add_TA(EMA(Cl(T)), legend="myEMA") 	   # doesn't