Project.addTestRunnerConfiguration(): Don't accidentally modify base config's buildSettings

[kinke]

This most likely doesn't affect dub itself, as it only works with a single configuration at a time. The problem has surfaced with reggae though (which can use multiple dub configurations at a time) - the mainSourceFile was removed from the base application config too.

[kinke]

[BuildSettings would have a .dup() method. Apparently very similar BuildSettings**Template** doesn't.]

[Geod24]

Maybe we could use

dub/source/dub/recipe/packagerecipe.d

Lines 462 to 489 in 09b35bc

	private T clone(T)(ref const(T) val)
	{
	import std.traits : isSomeString, isDynamicArray, isAssociativeArray, isBasicType, ValueType;
	static if (is(T == immutable)) return val;
	else static if (isBasicType!T) return val;
	else static if (isDynamicArray!T) {
	alias V = typeof(T.init[0]);
	static if (is(V == immutable)) return val;
	else {
	T ret = new V[val.length];
	foreach (i, ref f; val)
	ret[i] = clone!V(f);
	return ret;
	}
	} else static if (isAssociativeArray!T) {
	alias V = ValueType!T;
	T ret;
	foreach (k, ref f; val)
	ret[k] = clone!V(f);
	return ret;
	} else static if (is(T == struct)) {
	T ret;
	foreach (i, M; typeof(T.tupleof))
	ret.tupleof[i] = clone!M(val.tupleof[i]);
	return ret;
	} else static assert(false, "Unsupported type: "~T.stringof);
	}

?

[kinke]

Thx for the suggestion, much better now and still seems to work fine for reggae.