several other things to mention about 'roid rage'
several studies report no change in anger, not just this one, http://www.ncbi.nlm.nih.gov/pubmed/9154431
placebo causes people to act more aggressively under this myth, see http://www.sciencedaily.com/releases/2009/12/091208132241.htm
while there is some relationship with aggression, e.g. http://www.ncbi.nlm.nih.gov/pubmed/2029601, (a) this seems to be the difference between going from low to high testosterone -- not from high to higher testosterone, and (b) aggression is not the same thing as rage
when testosterone has been noted to increase aggressive behavior, it's usually observed as a response to perceived unfairness e.g. http://www.sciencedirect.com/science/article/pii/S002210311000260X
when rated on the subscales of (1) Hostility (2) Anger (3) Verbal Aggression (4) Physical Aggression, bodybuilders were more physically aggressive on average but not in any other domain (notably, not anger) -- I suspect this is because they are physically capable of being more aggressive, i.e. they have enough body mass that they can get away with it http://www.scirp.org/journal/PaperInformation.aspx?PaperID=33670
a friend argued elsewhere that this doesn't conclusively prove roid rage can't happen; which is fine, but, when there is very little evidence to suggest it exists and at most anecdotal report, this goes in the same category as folklore
in my broscience opinion: any instances of "roid rage" are probably instances of large hormone fluctuations -- say, from high T to low T due to stress or whatever. my late teens were pretty stressful and I went through a shit ton of mood swings / yelling at people constantly / fights / etc but after lifting more often and getting hormones under control I rarely had outward anger comparable to what it was in my late teens