fix ByteBuffer.grow (#2622)

* fix ByteBuffer.grow

---------

Co-authored-by: Christoffer Lerno <christoffer@aegik.com>

lib/std/io/stream/bytebuffer.c3

@@ -130,7 +130,7 @@ fn usz? ByteBuffer.available(&self) @inline @dynamic
 
 fn void ByteBuffer.grow(&self, usz n)
 {
-	n = math::next_power_of_2(n);
+	n = math::next_power_of_2(self.bytes.len + n);
 	char* p = allocator::realloc(self.allocator, self.bytes, n);
 	self.bytes = p[:n];
 }

releasenotes.md

@@ -9,6 +9,7 @@
 - Regression with npot vector in struct triggering an assert #2219.
 - Casting bitstruct to wider base type should be single step #2616.
 - Optional does not play well with bit ops #2618.
+- `Bytebuffer.grow` was broken #2622.
 
 ### Stdlib changes