[PATCH 4/4] gnus, notmuch: Consider text/plain patch attachments

[Kyle Meyer <kyle@kyleam.com>]

When inspecting attachments for generating an am-ready mbox, both
-notmuch and -gnus limit the operation to attachments with text/x-diff
or text/x-patch content types.  That has worked okay for me, though
I've run into a few cases where I couldn't apply a patch attachment
because it had a text/plain content type.

To do something useful in this case, check the file name to see
whether it looks like a patch.
---
 piem-gnus.el    |  3 ++-
 piem-notmuch.el |  3 ++-
 piem.el         | 10 +++++++---
 3 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/piem-gnus.el b/piem-gnus.el
index ca128fb..9dc4ae8 100644
--- a/piem-gnus.el
+++ b/piem-gnus.el
@@ -70,7 +70,8 @@ (defun piem-gnus-am-ready-mbox ()
                         (mapcar (lambda (handle)
                                   (and (listp handle)
                                        (piem-am-patch-attachment-p
-                                        (mm-handle-media-type handle))
+                                        (mm-handle-media-type handle)
+                                        (mm-handle-filename handle))
                                        (with-temp-buffer
                                          (mm-display-inline handle)
                                          (buffer-substring-no-properties
diff --git a/piem-notmuch.el b/piem-notmuch.el
index 8f5ef77..58e4d88 100644
--- a/piem-notmuch.el
+++ b/piem-notmuch.el
@@ -92,7 +92,8 @@ (defun piem-notmuch-am-ready-mbox ()
                      (delq nil
                            (mapcar (lambda (part)
                                      (and (piem-am-patch-attachment-p
-                                           (plist-get part :content-type))
+                                           (plist-get part :content-type)
+                                           (plist-get part :filename))
                                           (plist-get part :content)))
                                    (plist-get body :content)))))
            (cons (lambda ()
diff --git a/piem.el b/piem.el
index 9cc6a88..bee17c0 100644
--- a/piem.el
+++ b/piem.el
@@ -561,10 +561,14 @@ (defun piem-inject-thread-into-maildir (mid &optional message-only)
 \f
 ;;;; Patch handling
 
-(defun piem-am-patch-attachment-p (type)
+(defun piem-am-patch-attachment-p (type filename)
   "Return non-nil if an attachment should be treated as a patch.
-TYPE is a media type such as \"text/x-patch\"."
-  (member type '("text/x-diff" "text/x-patch")))
+TYPE is a media type such as \"text/x-patch\".  FILENAME is the
+attachment file name, if any."
+   (or (member type '("text/x-diff" "text/x-patch"))
+      (and filename
+           (equal type "text/plain")
+           (string-match-p "\\.patch\\'" filename))))
 
 (defun piem-extract-mbox-info (&optional buffer)
   "Collect information from message in BUFFER.
-- 
2.29.2