It's impossible to save a file regular expression pattern specified in the official Bamboo documentation when you create a new repository

Step to reproduce:

1. Create a new global repository pointed to some branch
2. Go to Edit Repository -> Advanced options -> Include / exclude files
3. Check 'Exclude all changes that match to the following pattern'
4. Copy a file pattern specified in the Bamboo documentation, e.g. **/dir1/file.txt. Link to the documentation: https://confluence.atlassian.com/bamboo0510/pattern-matching-reference-824479879.html
5. Click 'Save repository'

Expected result: Check that the settings have been saved
Actual result: The error message 'Invalid regex expression entered (Dangling meta character '*' near index 0 **/dir1/file.txt ^)' is shown (look at the screenshot)