retry_util: Force curl to use HTTP 1.1

This CL forces curl to use HTTP 1.1 due to intermittent error: "Error in
the HTTP2 framing layer".

TEST=./run_pytest ./lib/
TEST=./bin/cros_sdk --create --nouse-image

Change-Id: Icd6b57702a0bbc83845f4552d37d07ac7536f08c
Commit-Queue: Conor McNamara <>
Tested-by: Conor McNamara <>
Reviewed-by: Andrey Pronin <>
Reviewed-by: Stephane Belmon <>
(cherry picked from commit 4a0fcb57c0e871feaeee104dc8a152e58b10feb3)
Tested-by: Kangheui Won <>
Auto-Submit: Kangheui Won <>
Reviewed-by: Sam McNally <>
Commit-Queue: Sam McNally <>
diff --git a/lib/ b/lib/
index 1a976bb..9900567 100644
--- a/lib/
+++ b/lib/
@@ -383,7 +383,7 @@
     DownloadError: Whenever curl fails for any reason.
-  cmd = ['curl'] + curl_args
+  cmd = ['curl', '--http1.1'] + curl_args
   # These values were discerned via scraping the curl manpage; they're all
   # retry related (dns failed, timeout occurred, etc, see  the manpage for