-# produced different archives (GNU format is assumed). Namely, in the
-# second case the mode field of all members, except the first, was truncated
-# to lower 3 octets (& 0777).
+# produced different archives (GNU format is assumed). It was reported
+# by TAMUKI Shoichi on 2006-07-21 [1].
+#
+# The bug was due to tar being unable to discern between GNU and OLDGNU
+# formats and always assuming the latter. The main difference between
+# the two is that OLDGNU preserves all bits in the mode field, whereas
+# GNU format keeps only the lower 9 ones (mode & 0777).
+#
+# This was fixed on 2006-07-24 (commit f4e4adea80a) by making tar truncate
+# the mode field even in OLDGNU format. Obviously, the fix broke the
+# format backward compatibility, but it went unnoticed until 2009-10-03
+# (after all, the OLDGNU format is not in much use nowadays), when
+# Igor Zhbanov reported it [2].
+#
+# The final fix was applied on 2009-10-04.