download_file.py: Add --show-error option to curl invocation

Change-Id: I9e7708e6e425a0a3eeb4e22172746b3dc2b094a0

tools/download_file.py

diff --git a/tools/download_file.py b/tools/download_file.py
index c9736bf..c9c6ef0 100755
--- a/tools/download_file.py
+++ b/tools/download_file.py
@@ -103,7 +103,7 @@
 
   print('Download %s' % src_url, file=stderr)
   try:
-    check_call(['curl', '--proxy-anyauth', '-ksfo', cache_ent, src_url])
+    check_call(['curl', '--proxy-anyauth', '-ksSfo', cache_ent, src_url])
   except OSError as err:
     print('could not invoke curl: %s\nis curl installed?' % err, file=stderr)
     exit(1)