[indent]: when edit a file in split window, indent char was cleared

[shellRaining]

Describe the bug
when edit a file that open in two split window, one window's ident extmark was cleared

To Reproduce
Steps to reproduce the behavior:

1. open a file
2. using vsplit to open a new window
3. edit file in one of window, such as dd of cc

Expected behavior
indent mark not clear

Screenshots