cve-generate-chartdata: Handle unexpected files in the stats directory

A build of "stable/dunfell-nut" caused incorrect data to be added to the metrics
repo and resulted in script failures. Handle this situation better.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

scripts/cve-generate-chartdata

@@ -28,7 +28,11 @@ for branch in os.listdir(args.resultsdir):
     branchdir = os.path.join(args.resultsdir, branch)
     for f in os.listdir(branchdir):
         ts = f.split(".")[0]
-        rounded_ts = str(round_to_day(ts))
+        try:
+            rounded_ts = str(round_to_day(ts))
+        except ValueError:
+            # Couldn't parse a timestamp from filename
+            continue
         if rounded_ts not in counts:
             counts[rounded_ts] = {}
         if branch not in counts[rounded_ts]: