Sometimes when sprinting across a 1 block ditch you will not fall through. This is likely to be related to random fall damage due to lag. I first experienced this in 1.3.
I have a video demonstrating this.
If the attachment doesn't work try: http://youtu.be/FTetKnm7EVY
Linked issues
is duplicated by 15
MC-280176
Crossing gap without jumping
Resolved
MC-270877
Able to walk across one block gaps.
Resolved
MC-233434
You can run on Blocks that aren't connected each others (1 block of distance) without falling. It works only in some cases.
Resolved
MC-212361
Player can run on the air block (sometimes)
Resolved
MC-179559
Walking Diagonally Across Farmland
Resolved
relates to 3
Attachments
Comments 5
You can only clear exactly one block gap when fully sprinting. If you go at the gap at a slight angle you won't clear it. Also trying to go over with only a little start of 1-2 blocks you also won't make it because your sprint isn't fully engaged. Can seem buggy but it's just very strict about the circumstances. Maybe it could be changed to allow a bit more leeway so you wouldn't have to go straight in a cardinal direction but couldn't still clear wider gaps.
Running over a single block gap works as intended. See Teijo's comment for more information as to why it may randomly seem to not work.
That is an intended feature.