Revert "tests/libtest.sh: Print non-matching file on failure"

This reverts commit 71301d1824.

I was confused by the fact that the non-matching content was
empty and forgot we already did print it.

Reported-by: smcv

Closes: #390
Approved by: jlebon

tests/libtest.sh

@@ -138,7 +138,6 @@ assert_file_has_content () {
     if ! grep -q -e "$2" "$1"; then
         sed -e 's/^/# /' < "$1" >&2
         echo 1>&2 "File '$1' doesn't match regexp '$2'"
-	cat $1
         exit 1
     fi
 }