Incorrect handling of optional named operator when all values are null

[Paul-Martin]

UriTemplate.parse('/foo{?a,b,c}').expand({});
produces
"/foo?c="
should be
"/foo"

same for operators '&' and ';'

It seems to me that 'if (isFirstVarspec)' block starting at line 668 is unnecessary and removing it will resolve this issue without unwanted side effects.
.

[fxa]

Of course, you are right.
But I had some side effects, when removing this block.
I will add your test case and fix the bug