[Users] Claws 3.15.1 on Fedora - dirty

[edwardp at linuxmail.org]

Fedora now has version 3.15.1 of Claws in its repositories, but I
discovered the word 'dirty' is included in the version number of the
software.

From the mail headers:

X-Mailer: Claws Mail 3.15.1-dirty (GTK+ 2.24.31;
x86_64-redhat-linux-gnu)

Is there any particular reason for that designation (?) being included?
Something like 'alpha' or 'beta', is understandable, but 'dirty' looks 
rather unprofessional, IMHO.

Ed