= Fix Bugs =

== William ==

 * http://trac.sagemath.org/sage_trac/ticket/12689 -- (done) Segfault in solve_left for sparse matrices over ZZ
 * http://trac.sagemath.org/sage_trac/ticket/11358 -- (done) matrix multiplication over ZZ sometimes gives incorrect results
 * http://trac.sagemath.org/sage_trac/ticket/10281 -- (needs review) Multimodular echelon form over cyclotomic fields fails