Steps to reproduce:

1. Log in and turn on the visual editor.
2. Go to a random article like "Sundance Meadows Airport"
3. Click the Edit tab
4. After the cursor appears on the page, type a character

You will then see a white pawn at the end of the line of text you are editing.

Interestingly, it only seems to happen on articles that insert the cursor into a blank line at the top of the article. I'm not sure what determines that behavior, but it seems to be the behavior for the vast majority of en.wiki articles. The only article I haven't been able to reproduce the bug at so far is Lalage:
https://en.wikipedia.org/wiki/Lalage

I also can't reproduce the bug in my user sandbox:
https://en.wikipedia.org/wiki/User:Kaldari/sandbox

Confirmed in Safari and Chrome as well.

Pawn insertion from May 3:
https://en.wikipedia.org/w/index.php?title=Rubik%27s_360&diff=553360286&oldid=540708795

fran wrote:

Pawn ahoy: https://gerrit.wikimedia.org/r/gitweb?p=mediawiki/extensions/VisualEditor.git;a=blob;f=modules/ve/ce/ve.ce.Surface.js;h=7ad07c54370cb585ca264f78872fee0c83bd77a5;hb=HEAD#l1009

"git blame" says this section was worked on by Christian Williams, so maybe he'll know what's going on?

Can't reproduce this is master. It may have already been fixed, pending release?

(In reply to comment #1)

Steps to reproduce:

1. Log in and turn on the visual editor.
2. Go to a random article like "Sundance Meadows Airport"
3. Click the Edit tab
4. After the cursor appears on the page, type a character

You will then see a white pawn at the end of the line of text you are
editing.

Thanks; have updated the bug report accordingly.

Interestingly, it only seems to happen on articles that insert the cursor
into a blank line at the top of the article. I'm not sure what determines
that behavior, but it seems to be the behavior for the vast majority of
en.wiki articles.

That is bug 47790. It's not really a blank line in the document; it's the "potential" place to insert some new content, until you click into it and insert some, at which point it's whatever you type in. But it's not really very obvious to users what it is.

The only article I haven't been able to reproduce the bug at so far
is Lalage:
https://en.wikipedia.org/wiki/Lalage

A block-level slug only appears if the page starts with a template or other kind of generated content; any page that starts with one will get one (hence the pervasiveness). The alternative is not giving users the ability to insert content before a template if it happened to be at the start of a document, which would be even more confusing.

(In reply to comment #4)

Pawn insertion from May 3:
https://en.wikipedia.org/w/index.
php?title=Rubik%27s_360&diff=553360286&oldid=540708795

These kind of issues are precisely why there's a mandatory pre-save diff for users to read and agree it's fine. If there's a pawn inserted into the article, you're not meant to press save!

Confirming that this is fixed in master and wmf4; deployed in the normal deployment train.

verified for any page https://test2.wikipedia.org/

using chrome Version 26.0.1410.65 and firefox 25.