Excluding log fields of name mime_type for comparision.

This is because libmagic can return different results depending on
installation.

Note, this still doesn't fix all problems: smtp-entities sets md5
depending on the mime-type returned by libmagic ...

testing/scripts/diff-canonifier-external

@@ -2,4 +2,7 @@
 #
 # Default canonifier used with the trace-based tests in testing/external/*.
 
-`dirname $0`/diff-remove-timestamps | `dirname $0`/diff-remove-uids
+`dirname $0`/diff-remove-timestamps \
+    | `dirname $0`/diff-remove-uids \
+    | `dirname $0`/diff-remove-mime-types \
+    | `dirname $0`/diff-remove-abspath

testing/scripts/diff-remove-mime-types

@@ -0,0 +1,22 @@
+#! /usr/bin/awk -f
+#
+# A diff canonifier that removes all MIME types because libmagic output
+# can differ between installations.
+
+BEGIN { FS="\t"; OFS="\t"; column = -1; }
+
+/^#fields/ {
+    for ( i = 2; i < NF; ++i )
+        if ( $i == "mime_type" )
+            column = i-1;
+}
+
+column >= 0 {
+    if ( $column != "-" )
+        # Mark that it's set, but ignore content.
+        $column = "+";
+}
+
+{
+    print;
+}

testing/scripts/diff-remove-uids

@@ -2,7 +2,7 @@
 #
 # A diff canonifier that removes all connection UIDs.
 
-BEGIN { IFS="\t"; OFS="\t"; }
+BEGIN { FS="\t"; OFS="\t"; }
 
 column > 0 {
     $column = "XXXXXXXXXXX";