Brian Henderson [off-list ref] writes:
+# dh_test is a test helper function which takes 1) some file data, 2) some
+# change of the file data, creates a diff and commit of the changes and passes
+# that through diff-highlight.
+# The optional 3rd parameter is the expected output of diff-highlight minus the
+# diff/commit header. This parameter is given directly to printf as the format
+# string (in order to properly handle ascii escape codes; CW, CR), so any '%'
+# need to be doubled to protect it.
My mistake. All three are given directly to printf as the format
string, so it is misleading to single out $3 when warning the
callers about '%'.
Sorry about that.