plugin attachment: remove "path" from attachment once used:

"path" refers to a local path of a file, we don't want to store it in database as the file
may be in a temporary location, or even be a temporary file. So once the file has been
uploaded, we remove it.

sat/plugins/plugin_misc_attach.py

@@ -59,15 +59,19 @@ class AttachPlugin:
 
         for attachment in attachments:
             try:
-                path = Path(attachment["path"])
+                # we pop path because we don't want it to be stored, as the image can be
+                # only in a temporary location
+                path = Path(attachment.pop("path"))
             except KeyError:
                 log.warning("no path in attachment: {attachment}")
                 to_delete.append(attachment)
                 continue
 
             if "url" in attachment:
-                log.warning("invalid attachment: unknown URL")
-                to_delete.append(attachment)
+                url = attachment.pop('url')
+                log.warning(
+                    f"unexpected URL in attachment: {url!r}\nattachment: {attachment}"
+                )
 
             try:
                 name = attachment["name"]