Noticed this image circulating a fair bit today and immediately questioned its authenticity as that's too good of a mistake to not get noticed. So, as ya do, I had a quick properly look and from what I can see so far, it's a fake.
1) The 'dot' on the I within Tesco's font (which is actually named 'Tesco') does not have a square 'dot' [Purple arrow]. Note the other two lines [blue arrows] (one I wrote and the original label one) are circular.
2) [Blue arrow] There's a very faint area of white after the 't', which is usually very noticeable when people use certain tools to remove objects in pictures, notably the clone stamp in Photoshop.
3) [Red arrow] There's a slight lift in brightness at the base of the 'i', which isn't visible for any other letter in that sentence.
There we go, nice try. ;)