ID 491883 - mari.ShelfItem.saveAs() does not export Shelf items

Problem summary
mari.ShelfItem.saveAs() does not export Shelf items

Customer reported version
Mari 4.7v2

Customer reported platform
CentOS 7

Steps to reproduce

1) Open any Project

2) Run the following script in the Python Console, replacing <FOLDER PATH> with the path to an empty folder:

folder = '<FOLDER PATH>'
shelf = mari.shelves.find('Basic Brushes')

for item in shelf.list():
    print item.name()
    itemFilePath = os.path.join(folder, '{itemName}.msi'.format(itemName=item.name()))
    item.saveAs(itemFilePath)

3) Check the folder

Expected behaviour
The folder should contain the exported .msi Shelf Item files from the 'Basic Brushes' Shelf.

Actual behaviour
The Shelf Items were not exported.

Workaround
Unknown.

Reproduced by support
This bug has been reproduced in:
Mari 4.7v4 - Windows 10 - CentOS 7.9
Mari 4.7v1 - Windows 10 - CentOS 7.9 - regression

Unable to reproduce bug in:
Mari 4.6v4 - Windows 10 - CentOS 7.9

Earliest version tested
Mari 4.6v4 - This issue doesn't appear in this version and has regressed