Bug 1886737 - fetch-content: fix download_to_memory retries. r=releng-reviewers,bhearsum DONTBUILD

Previously we would append data from each download to the previous,
failed one(s).

Differential Revision: https://phabricator.services.mozilla.com/D205315

Author: jcristau

src/taskgraph/run-task/fetch-content

@@ -284,11 +284,11 @@ def download_to_path(url, path, sha256=None, size=None, headers=None):
 def download_to_memory(url, sha256=None, size=None):
     """Download a URL to memory, possibly with verification."""
 
-    data = b""
     for _ in retrier(attempts=5, sleeptime=60):
-        try:
-            log("Downloading %s" % (url))
+        data = b""
+        log("Downloading %s" % (url))
 
+        try:
             for chunk in stream_download(url, sha256=sha256, size=size):
                 data += chunk