[COMMITTED][PATCH] debuginfod-client.c: Don't print empty line in header_callback

[Aaron Merey <amerey@redhat.com>]

libcurl passes an empty line to header_callback indicating the end
of the response's HTTP headers.

Currently this empty line is printed to the debuginfod_client's
verbose_fd with a "header" prefix:

    $ echo $DEBUGINFOD_URLS
    https://debuginfod.fedoraproject.org/
    $ debuginfod-find -vv debuginfo e2bbf033b548021c37866429f12a99bd33bd6e8d
    [...]
    header x-fedora-requestid: ZULLx0PPA8nmj8c8Hw-RtAACgAE
    header server: Apache
    header
    [...]

Prevent this unnecessary line of output by only printing non-empty
lines in header_callback.

Signed-off-by: Aaron Merey <amerey@redhat.com>
---
 debuginfod/debuginfod-client.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/debuginfod/debuginfod-client.c b/debuginfod/debuginfod-client.c
index 6882cb19..dcf05031 100644
--- a/debuginfod/debuginfod-client.c
+++ b/debuginfod/debuginfod-client.c
@@ -568,7 +568,9 @@ header_callback (char * buffer, size_t size, size_t numitems, void * userdata)
   struct handle_data *data = (struct handle_data *) userdata;
   if (size != 1)
     return 0;
-  if (data->client && data->client->verbose_fd >= 0)
+  if (data->client
+      && data->client->verbose_fd >= 0
+      && numitems > 2)
     dprintf (data->client->verbose_fd, "header %.*s", (int)numitems, buffer);
   // Some basic checks to ensure the headers received are of the expected format
   if (strncasecmp(buffer, "X-DEBUGINFOD", 11)
-- 
2.41.0