Unexpected path when using partial reference in parent field of Create

Reproduction steps:

• Ensure you use an advanced user
• Click on create page button from Main.WebHome
• Click on the pencil in "Location" to open advanced fields
• In "Parent" field put ".X..Y."
• In "Name" field put "Test"
• Click create

Expected result:

• the create button should be disabled and a message should appear saying that the Parent reference is wrong

Obtained result:

• Clicking on create leads to a page with URL: "edit/Main/X/Main/Y/Main/Test/WebHome" and saving it creates a page with corresponding reference "Main.X.Main.Y.Main.Test.WebHome"

Note that "Main" here appears because we started from "Main.WebHome" it would be different if starting from a different space.