[exim] headers_add headers_remove

Hi gang

I recently updated to 4.51 and think something may have happened to
the headers_add and headers_remove features I was relying on.
Currently, I have:

headers_add        = ${if mathch{$header_list-post:} {\<mailto:(.*)\>} \
                     {${if def:header_reply-to: \
                     {X-Orig-reply-to: $header_reply-to:\nReply-To: < 
$1>} \
                     {Reply-to: <$1>} }} \
                     {} }

headers_remove      = ${if and { \
                     {def:header_reply-to:} {def:header_list-post:}\
                     } {reply-to} fail }

Failing some possible mistakes in my transcription, is there any
reason this wouldn't work in 4.51? It appears it isn't currently
working and it did in 4.43 (or whatever the previous release to 4.50
was).

-Michael

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I never teach my pupils; I only attempt to provide the conditions in  
which they can learn.
                 --Albert Einstein