+PH/22 Added support for macro redefinition, and (re)definition in between
+ driver and ACL definitions.
+
+PH/23 The cyrus_sasl authenticator was expanding server_hostname, but then
+ forgetting to use the resulting value; it was using the unexpanded value.
+
+PH/24 The cyrus_sasl authenticator was advertising mechanisms for which it
+ hadn't been configured. The fix is from Juergen Kreileder, who
+ understands it better than I do:
+
+ "Here's what I see happening with three configured cyrus_sasl
+ authenticators configured (plain, login, cram-md5):
+
+ On startup auth_cyrus_sasl_init() gets called for each of these.
+ This means three calls to sasl_listmech() without a specified mech_list.
+ => SASL tests which mechs of all available mechs actually work
+ => three warnings about OTP not working
+ => the returned list contains: plain, login, cram-md5, digest-md5, ...
+
+ With the patch, sasl_listmech() also gets called three times. But now
+ SASL's mech_list option is set to the server_mech specified in the the
+ authenticator. Or in other words, the answer from sasl_listmech()
+ gets limited to just the mech you're testing for (which is different
+ for each call.)
+ => the return list contains just 'plain' or 'login', 'cram-md5' or
+ nothing depending on the value of ob->server_mech.
+
+ I've just tested the patch: Authentication still works fine,
+ unavailable mechs specified in the exim configuration are still
+ caught, and the auth.log warnings about OTP are gone."
+
+PH/25 When debugging is enabled, the contents of the command line are added
+ to the debugging output, even when log_selector=+arguments is not
+ specified.
+
+PH/26 Change scripts/os-type so that when "uname -s" returns just "GNU", the
+ answer is "GNU", and only if the return is "GNU/something" is the answer
+ "Linux".
+
+PH/27 $acl_verify_message is now set immediately after the failure of a
+ verification in an ACL, and so is available in subsequent modifiers. In
+ particular, the message can be preserved by coding like this:
+
+ warn !verify = sender
+ set acl_m0 = $acl_verify_message
+
+ Previously, $acl_verify_message was set only while expanding "message"
+ and "log_message" when a very denied access.
+