Comment 13 for bug 404256

Alright, tried this on linux 32-bit now too. The patch has the same effect as on 64-bit.

I did realize that there are actually two exceptions being thrown depending on the graph:

igraph.core.InternalError: Error at community.c:1185: , No shifts could be applied during a cycle of the Implicitly restarted Arnoldi iteration. One possibility is to increase the size of NCV relative to NEV

igraph.core.InternalError: Error at community.c:1185: , Maximum number of iterations reached

I followed the advice of the first exception and bumped NCV to 5. The code has now run for 500 graphs without either exception being thrown. It is somewhat slower, however.