Fix buffer growth in AllocAppender.

The newly introduced "withAlloc" wrapper was not accepting arguments by reference, thus discarding the new array value returned by reallocate().

source/vibe/internal/array.d

@@ -185,7 +185,7 @@ struct AllocAppender(ArrayType : E[], E) {
 		reserve(new_size - m_data.length + m_remaining.length);
 	}
 
-	private auto withAlloc(string method, ARGS...)(ARGS args)
+	private auto withAlloc(string method, ARGS...)(auto ref ARGS args)
 	{
 		static if (is(RCIAllocator)) {
 			if (!m_rcAlloc.isNull) return __traits(getMember, m_rcAlloc, method)(args);
@@ -252,6 +252,14 @@ unittest {
 	assert(app.data == "foo");
 }
 
+unittest {
+	auto app = AllocAppender!string(theAllocator);
+	app.reserve(3);
+	app.put("foo");
+	app.put("bar");
+	assert(app.data == "foobar");
+}
+
 
 struct FixedAppender(ArrayType : E[], size_t NELEM, E) {
 	alias ElemType = Unqual!E;