I found and fixed an off-by-one that manifested itself in a cut-off property in the nar.properties file (in my case, there was a line 'amd64-Linux-gc.libs.binding=executable' instead of 'amd64-Linux-gcc.libs.binding=executable').

When finding the aol from a classifier string a la
'amd64-Linux-gcc-executable' we really want the first part up to
and excluding the last dash. Without this change, one more character
would be stripped, though.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>