[FS#1480] Interface names starting with a number causes things to break

[LEDE Bugs]

A new Flyspray task has been opened.  Details are below. 

User who did this - HD7544 (HD7544) 

Attached to Project - OpenWrt/LEDE Project
Summary - Interface names starting with a number causes things to break
Task Type - Bug Report
Category - Base system
Status - Unconfirmed
Assigned To - 
Operating System - All
Severity - Low
Priority - Very Low
Reported Version - Trunk
Due in Version - Undecided
Due Date - Undecided
Details - Supply the following if possible:
 - Device problem occurs on
 - Software versions of OpenWrt/LEDE release, packages, etc.
 - Steps to reproduce
   
I've noticed this across several devices: WRT1900ACv2, TP-Link WDR-3600 and RT-N13U so far. After creating a switch VLAN and assigning it an interface, DHCP stops working if interface name does not start with an alpha character. Naming an interface with the VLAN number (or any number causes this breakage).  Only way to to recover is to manually assign an IP address in subnet and rename the interface to something like LAN[VLAN_ID]. 

Once this is done, all functions as it should. 
 

More information can be found at the following URL:
https://bugs.openwrt.org/index.php?do=details&task_id=1480