Issue #24514: tarfile now tolerates number fields consisting of only whitespace.
diff --git a/Lib/tarfile.py b/Lib/tarfile.py
index e3a2bb3..6d8d36c 100755
--- a/Lib/tarfile.py
+++ b/Lib/tarfile.py
@@ -178,7 +178,8 @@
             n = -(256 ** (len(s) - 1) - n)
     else:
         try:
-            n = int(nts(s, "ascii", "strict") or "0", 8)
+            s = nts(s, "ascii", "strict")
+            n = int(s.strip() or "0", 8)
         except ValueError:
             raise InvalidHeaderError("invalid header")
     return n