cdef processing picks processed variable instead of original

[Mrten]

I'd like to STACK a couple of variables that are the min, 25%, median, 75% and max of a datastream (in this case, processing times of webpages).

The plugin outputs the times as absolute values and I'd like to correct that with cdefs. However, when I use the following:

sv0.draw AREASTACK

sv1.draw AREASTACK
sv1.cdef sv1,sv0,-

sv2.draw AREASTACK
sv2.cdef sv2,sv1,-

sv3.draw AREASTACK
sv3.cdef sv3,sv2,-

[.etc.]

The generated graph is wrong (too high) because this gets translated to rrdgraph as:

'CDEF:acdefsv1=asv1,asv0,-' \
'CDEF:acdefsv2=asv2,acdefsv1,-' \
'CDEF:acdefsv3=asv3,acdefsv2,-' \
'CDEF:acdefsv4=asv4,acdefsv3,-' \

(removed the parts that werent necessary to illustrate the problem) acdefsv2 is not sv2 - sv1 as expected but, ultimately, sv2 - sv1 + sv0 because the cdef processing picks acdefsv1 instead of asv1 in the CDEF.

[shapirus]

#664 may be related.