The documentation of GNU patch states:
You can create a file by sending out a diff that compares /dev/null or an empty file dated the
Epoch (1970-01-01 00:00:00 UTC) to the file you want to create.
This is used, for example by (GNU) diff -ruN, where the -N option reads:
-N, --new-file
treat absent files as empty
Currently, this implementation of patch would return Edit on such an input instead of the expected Create