Incorrect initial candidate connection when moving top block of stack

[cpcallen]

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Description

When performing a keyboard move on the top (root) block of a stack of statement blocks, it initially begins the move without a connection candidate. This means that:

• Pressing down arrow once causes it to have the connection candidate it should have had initially.
• Pressing enter without moving drops the block in its original location on the workspace, but instead of reconnecting the rest of the stack, the rest of the stack is bumped.

Reproduction steps

1. Select top block of a stack.
2. Press m to begin move. Observe no insertion marker shown.
3. Press down arrow. Observe that a candidate connection for the block's original connection is now shown.
4. Press down arrow several more times, then up arrow several times; observe block now moves as expected.
5. Press esc to end move.
6. Press m to begin a new move.
7. Press enter to end move without moving. Observe that block is droped in place but rest of stack is bumped rather than reconnected.

Stack trace

No console output observed.

Screenshots

Using the steps given above:

Screen.Recording.2025-09-15.at.11.45.14.mov

Browsers

Chrome desktop

Additional Info

We will also need to add a test for this scenario, because it was inadvertently omitted from #695.

[gonfunko]

This was fixed by RaspberryPiFoundation/blockly#9593