Setting jira.clone.prefix to null or blank results in a space added as a prefix

Cloning an issue with jira.clone.prefix set to null or blank results in a space prefix added to the clone.

For illustration purposes:

starting ticket summary: 'TestingCloning3'

After first clone (and rolling the count in the summary): ' TestingCloning2'

After clone of the first clone (and rolling the count in the summary): ' TestingCloning3'

Seems to be common: https://answers.atlassian.com/questions/64026/removed-clone-prefix-adds-blank-space