In 3.7.2, spaces before <em> or <i> tags get removed after conversion to KEPUB

[hengyu95]

Bug Checklist

These items are mandatory. If you need help finding this information submit the
bug report with as much completed as you can and ask for help finding the rest.

• I am using the latest version of calibre to report this bug, which is:
• I am using an official calibre release, not one from a third party (e.g.
  your Linux distro, Flatpak, Chocolatey package, Homebrew, etc.)
• I am using the latest version of this plugin, which is:
• My operating system is Windows 11
• I have included the full, complete, unmodified debug log from calibre
  • Directions for getting the debug log are under the "Logs" header below.
• I have translated the text in any screenshots and logs to English, or all
  screenshots and logs included are in English.

These items are optional. Fill in as much of them as possible. If something is
not applicable to your bug report, note that.

• I have installed the Scramble Epub plugin (see
  https://www.mobileread.com/forums/showthread.php?t=267998) and will attach
  a scrambled copy of the book I'm having problems with (attach a file by
  dragging and dropping onto the Github editor).
  • If this is a conversion bug, I will also attach a scrambled copy of
    the converted book.
• The path to my calibre library or to a book in my calibre library has
  non-ASCII characters: yes/no
• If I am using Windows 10, I (have/have not) enabled Windows' beta support
  for Unicode (see
  https://www.mobileread.com/forums/showpost.php?p=3988195&postcount=2052)
• If I am using Windows 10, does this bug happens with beta Unicode support
  both enabled and disabled, only when enabled, or only when disabled?

Describe the bug

In the EPUB to KEPUB conversion, spaces before italics all get removed.

Steps to Reproduce

Convert any EPUB to KEPUB via sending it to Kobo

Expected behavior

Spaces before italics remain

Actual behaviour

Spaces before italics are deleted. This is corroborated by many other users on the mobileread forums.

Screenshots

Original EPUB

Converted KEPUB

Logs

N/A, conversion itself "works"

Additional context

Add any other information you think might be helpful.

[chocolatechipcats]

Also appears to affect tags: https://www.mobileread.com/forums/showpost.php?p=4474070&postcount=3159