[BUG] org-list-struct-apply-struct overrides src block indentation (was: [BUG] Source block indentation does not work properly for yaml-mode [9.6.6 ( @ /home/user/.emacs.d/elpa/org-9.6.6/)])

[Ihor Radchenko <yantar92@posteo.net>]

Using a similar example, another indentation bug has been revealed:

1. emacs -Q
2. Create an Org file with the following contents:

- 1
  - 2
    - 3
      - 4
- 5
  #+begin_src yaml
    a:
      b:
        c:
          d:
  #+end_src

Everything indented using spaces, including "d:" that uses 8 spaces,
which should remain spaces since yaml-mode uses spaces for indentation.

3. M-x whitespace-mode
4. Move point to item 5 and press M-<right> 3 times
5. Observe "d:" indented using two tabs with all the spaces replaced by tabs.

The cause is the following line in `org-list-struct-apply-struct'
[[file:~/Git/org-mode/lisp/org-list.el::indent-line-to (+ (org-current-text-indentation) delta)))]]

It calls `indent-line-to' that replaces spaces with tabs according to
current value of indent-tabs-mode in Org buffer.

-- 
Ihor Radchenko // yantar92,
Org mode contributor,
Learn more about Org mode at <https://orgmode.org/>.
Support Org development at <https://liberapay.com/org-mode>,
or support my work at <https://liberapay.com/yantar92>