I have a very simple EditText, as follows:
It looks like you can work around this problem by calling EditText.setError() with a SpannableStringBuilder object rather than a String.
int ecolor = xxxx; // whatever color you want
String estring = "Input is incorrect";
ForegroundColorSpan fgcspan = new ForegroundColorSpan(ecolor);
SpannableStringBuilder ssbuilder = new SpannableStringBuilder(estring);
ssbuilder.setSpan(fgcspan, 0, estring.length(), 0);
myedittext.setError(ssbuilder);