temp: precise memory-bio reason

Author: aidangarske

.github/examples-manifest.yml

@@ -872,10 +872,13 @@ examples:
       # exist in this dir. Every server loops until SIGINT, so all pairs are
       # server_exit: killed.
       # NOT RUN: hangs on DTLS 1.3, which it selects whenever this profile's
-      # --enable-dtls13 is on. Measured: with the use-after-free fixed it now
-      # completes fully on DTLS 1.2 (accept + client msg), so the remaining
-      # stall is DTLS 1.3 specific and looks like a wolfSSL memory-BIO issue
-      # rather than an example bug. Re-enable once that is resolved.
+      # --enable-dtls13 is on. With the use-after-free fixed it completes fully
+      # on DTLS 1.2, so this is DTLS 1.3 specific and looks like wolfSSL, not
+      # the example: DTLS assumes one read == one datagram, but BIO_s_mem is a
+      # byte stream, so the larger 1.3 flight ends mid-record and wolfSSL logs
+      # "Partial record received, dropping" / "Silently dropping DTLS message:
+      # -370". The bytes are already consumed and nothing retransmits, so both
+      # sides then block on read forever. Re-enable once that is fixed.
       # A complete DTLS server rather than a self-contained demo: bare exec just
       # blocks in poll() until the step times out. It has no dedicated client.
       # export writes dtls_{server,client}_session.bin; import reads them, so this