Accepting completion in := lua cmdline removes prior input

[disrupted]

Make sure you have done the following

• Updated to the latest version of blink.cmp
• Searched for existing issues and documentation (try <C-k> on https://cmp.saghen.dev)

Bug Description

When using := cmdline (short form for :lua ={expr}) I noticed that when I accept a completion candidate it gets inserted but prior input is deleted.

repro

| is cursor position

1. :=vim.tbl_|
2. accept tbl_deep_extend completion
3. :=tbl_deep_extend|

counter check long form

the same works for the long form

1. :lua =vim.tbl_|
2. accept tbl_deep_extend completion
3. :lua =vim.tbl_deep_extend|

Relevant configuration

{
  "saghen/blink.cmp",
  version = "*",
  opts = {},
}

neovim version

v0.11.0-dev-1756+gc091bc3b9a

blink.cmp version

v0.12.3

[MrConnorKenway]

Similar cmdline completion issues have been occurred multiple times in previous releases (#883 (comment), #887 (comment)), is there any chance for blink to have unit tests to test them automatically?

[memchr]

possible workaround: append a space after := , and the previous input will be kept.