(Android) Splitting and merging a Paragraph/Heading block doesn't work correctly

[geriux]

Description

While running the writing flow tests on the Mobile editor release 1.48.0 an issue was found regarding splitting and merging content in a Paragraph/Heading block.

Step-by-step reproduction instructions

1. Open the mobile editor
2. Write (or paste) a paragraph with a few lines
3. Set the caret by the half of the paragraph
4. Press Enter (Intro) to split the block into two. (if using the simulator, use the device keyboard)
5. Move the caret a few words.
6. Delete all those words until the blocks merge.
7. See that the original content of the first Paragraph block shows up causing the content to be duplicated.

Expected behaviour

The two blocks should merge without any content duplication.

Actual behaviour

After emerging the two blocks the original content of the first Paragraph block returns causing content duplication.

Screenshots or screen recording (optional)

Screenrecorder-2021-03-02-14-29-38-946.mp4

Device information

• Device: Redmi Note 8T (Or Pixel simulator)
• Operating system: Android 10

[geriux]

This is a regression from #28505.

[cameronvoell]

@geriux I was taking a look at this and don't have a solution yet but I did find some simpler steps to reproduce:

1. Paste text
2. move cursor halfway and use emulator keyboard to press enter
3. Switch to HTML mode
4. Notice incorrect text
   *Note if you use those same steps with your computers physical keyboard controlling the emulator to press enter, the correct text will show in html mode.
   

[geriux]

Reopening since the first approach to fix it didn't work.

[geriux]

I just reverted the PR I made to try to fix it but ended up not working.