Repeating `gb` once when selecting Multi-Cursors means subsequent `gb` are repeated that amount

Describe the bug
If you use gb with a number, subsequent uses of gb are repeated that same amount. Eg 10gb gb would result in 20 cursors, not 11.

Similarly, if I do gb, 10gb, gb, I get 21 cursors instead of 12.

To Reproduce

Lets say I have 10 lines, each with the same single word

vim
vim
...
vim
vim

Scenario A) I put a cursor on the first line, and in normal mode do 5gb then gb.

Scenario B) I put a cursor on the first line, and in normal mode do gb, 5gb, gb.

Expected behavior
Scenario A) I would expect 6 cursors but there are 10.

Scenario B) I would expect 7 cursors but there are 10 (there would be 11 if there were more lines).

Screenshots

Environment (please complete the following information):

• Issue Type: Bug
• Extension Name: vim
• Extension Version: 1.10.2
• OS Version: Linux x64 5.2.14-arch2-1-ARCH
• VSCode version: 1.38.0

Additional context
N/A

Start by reproducing scenarios A and B in the VS Code Vim extension and trace the normal-mode gb handling. Done means repeated gb adds only the requested number of cursors: 5gb then gb yields 6, and gb then 5gb then gb yields 7.