Simplify bad http client pruning

src/apiutils.nim

@@ -58,17 +58,15 @@ template fetchImpl(result, fetchBody) {.dirty.} =
   if token.tok.len == 0:
     raise rateLimitError()
 
-  var
-    client = pool.acquire(genHeaders(token))
-    badClient = false
-
   try:
-    let resp = await client.get($url)
-    result = await resp.body
+    var resp: AsyncResponse
+    pool.use(genHeaders(token)):
+      resp = await c.get(url)
+      result = await resp.body
 
-    if resp.status == $Http503:
-      badClient = true
-      raise newException(InternalError, result)
+      if resp.status == $Http503:
+        badClient = true
+        raise newException(InternalError, result)
 
     if result.len > 0:
       if resp.headers.getOrDefault("content-encoding") == "gzip":
@@ -89,8 +87,6 @@ template fetchImpl(result, fetchBody) {.dirty.} =
     if "length" notin e.msg and "descriptor" notin e.msg:
       release(token, invalid=true)
     raise rateLimitError()
-  finally:
-    pool.release(client, badClient=badClient)
 
 proc fetch*(url: Uri; api: Api): Future[JsonNode] {.async.} =
   var body: string