Merge of concurrent page edits seems broken

Automatic merge of concurrent edits seems to fail in most cases. Please find attached an example page that fails merge consistently. In this example we have a page with uniquely numbered lines. Multiple users edit the page but each one edits a different part of it. Since the page text lines have numbers I do not expect any merge conflict as the merge algorithm must look at the context surrounding the change and notice they are different.

Reproduction steps:
1. Save the example page.
2. User 1 starts editing one section, say number 3.
3. User 2 starts editing another section, say number 5.
4. User 2 saves.
5. User 1 tries to save. This user will see a conflict.