AdsorbingSurfactantEquation intermittently diverges on Linux with scipy solver

[guyer]

Test of AdsorbingSurfactantEquation fails on linux with scipy solvers, but not always?!?

accVar seems to agree with results on a Mac for first 34 steps, but then starts to diverge and ends up nan.

Mac:

35 [ 1.00000000e-40  1.50000000e-40  1.81421010e-40  1.64442283e-40
  1.00000000e-40  1.50000000e-40  2.37157979e-40  2.95115638e-40
  0.00000000e+00  0.00000000e+00  1.81421010e-40  2.95115638e-40
  0.00000000e+00  4.02672701e-01 -2.16840434e-19  1.64442283e-40
  0.00000000e+00  4.02672701e-01  3.00000000e-40  4.69493579e-01
  1.00000000e-40  0.00000000e+00 -2.16840434e-19  4.69493579e-01
  3.00000000e-40]

vs Linux:

35 [  1.00000000e-40   1.50000000e-40   1.81421010e-40   1.64442283e-40
   1.00000000e-40   1.50000000e-40   2.37157979e-40   2.95115638e-40
   0.00000000e+00  -2.40741243e-35   1.81421010e-40   2.95115638e-40
   0.00000000e+00   4.02672701e-01  -2.16840434e-19   1.64442283e-40
   0.00000000e+00   4.02672701e-01   3.00000000e-40   4.69493579e-01
   1.00000000e-40  -2.40741243e-35  -2.16840434e-19   4.69493579e-01
   3.00000000e-40]