Fixes #6100.

tests/async/t6100.nim

@@ -0,0 +1,15 @@
+discard """
+  file: "t6100.nim"
+  exitcode: 0
+  output: "10000000"
+"""
+import asyncdispatch
+
+let done = newFuture[int]()
+done.complete(1)
+
+proc asyncSum: Future[int] {.async.} =
+  for _ in 1..10_000_000:
+    result += await done
+
+echo waitFor asyncSum()

tests/async/tfuturestream.nim

@@ -18,8 +18,8 @@ var fs = newFutureStream[int]()
 
 proc alpha() {.async.} =
   for i in 0 .. 5:
-    await sleepAsync(1000)
     await fs.write(i)
+    await sleepAsync(1000)
 
   echo("Done")
   fs.complete()