`:'<,'>s` produces incorrect result if replacement has more lines than search pattern.

Describe the bug
:'<,'>s produces an incomplete result if the replacement pattern results in more lines than search pattern.

To Reproduce

1. Open a new file.
2. Write five new lines, each containing the word hello.
3. Enter visual line mode and select all five lines.
4. Type :s/hello/world\n\n/g and press enter (will expand to :'<,'>s/hello/world\n\n/g automatically since multiple lines are selected.)
5. Only the first two lines are replaced, rather than all five of the lines. (I would assume the replacement is not updating some internal value used to keep track of which lines in the file are part of the requested range for the command.)

Expected behavior
Each of the five originally selected lines should be replaced with world\n\n, resulting in a 15-line file. The final file should look like this:

world


world


world


world


world

Environment (please complete the following information):

• Extension (VsCodeVim) version: 0.16.6
• VSCode version: 1.26.1
• OS: Linux x64 4.18.16-100.fc27.x86_64 (Fedora)

Reproduce the issue in the VSCodeVim extension using visual line mode and the :'<,'>s/hello/world\n\n/g command. Trace how the selected range is handled when the replacement expands to multiple lines. Done means all five selected lines are replaced and the resulting file has 15 lines as shown in the report.