When rrd file contains a space graph is missing

[warrmr]

When an rrd file contains a space the graph does not render.

./asa.warrillow.local/snmp:
-rw-r--r-- 1 root root 10064 Mar 16 21:52 if_octets-Adaptive Security Appliance 'Ethernet0_0' interface.rrd
-rw-r--r-- 1 root root 10064 Mar 16 21:52 if_octets-Adaptive Security Appliance 'Ethernet0_1' interface.rrd
-rw-r--r-- 1 root root 10064 Mar 16 21:52 if_octets-Adaptive Security Appliance 'Ethernet0_2' interface.rrd
-rw-r--r-- 1 root root 10064 Mar 16 21:52 if_octets-Adaptive Security Appliance 'Ethernet0_3' interface.rrd
-rw-r--r-- 1 root root 10064 Mar 16 21:50 if_octets-Adaptive Security Appliance 'Ethernet0_4' interface.rrd
-rw-r--r-- 1 root root 10064 Mar 16 21:52 if_octets-Adaptive Security Appliance 'Ethernet0_5' interface.rrd
-rw-r--r-- 1 root root 10064 Mar 16 21:50 if_octets-Adaptive Security Appliance 'Ethernet0_6' interface.rrd
-rw-r--r-- 1 root root 10064 Mar 16 21:52 if_octets-Adaptive Security Appliance 'Ethernet0_7' interface.rrd
-rw-r--r-- 1 root root 10064 Mar 16 21:52 if_octets-Adaptive Security Appliance 'inside' interface.rrd
-rw-r--r-- 1 root root 10064 Mar 16 21:52 if_octets-Adaptive Security Appliance 'Internal-Data0_0' interface.rrd
-rw-r--r-- 1 root root 10064 Mar 16 21:50 if_octets-Adaptive Security Appliance 'Internal-Data0_1' interface.rrd
-rw-r--r-- 1 root root 10064 Mar 16 21:52 if_octets-Adaptive Security Appliance '_internal_loopback' interface.rrd
-rw-r--r-- 1 root root 10064 Mar 16 21:52 if_octets-Adaptive Security Appliance 'outside' interface.rrd
-rw-r--r-- 1 root root 10064 Mar 16 21:52 if_octets-Adaptive Security Appliance 'Virtual254' interface.rrd

[warrmr]

Using setting the instance value to "IF-MIB::ifName" instead of "IF-MIB::ifDescr" works around this issue.