Empty equation systems during initialization

[Lennart Ochel]

I figured out one more case that let the initialization fail. Please check the following model:

msl31/Modelica.Mechanics.MultiBody.Examples.Loops.PlanarLoops_analytic.mos

This example produces this error messages:

Notification: The given system is mixed-determined.   [index > 0]
Notification: The given system is mixed-determined.   [index > 1]
Notification: The given system is mixed-determined.   [index > 2]
Notification: The given system is mixed-determined.   [index > 3]
Warning: No system for the symbolic initialization was generated. A method using numerical algorithms will be used instead

The example fails, since there are equation systems without variables:

unknown partition
========================================

Variables (0)
========================================


Equations (1, 3)
========================================
1/1 (3): {0.0, 0.0, 1.0} = {0.0, 0.0, 1.0}   [dynamic]


State Sets
========================================


Incidence Matrix (row: equation)
========================================
number of rows: 3
1:
2:
3:


Transpose Incidence Matrix (row: var)
========================================
number of rows: 0


no matching

[Lennart Ochel]

Fixed in r24301.
Now, empty systems are skipped, but its equations are used for consistence check.

[Dietmar Winkler]

It doesn't make sense to keep closed ticket in the "Future" milestone that were simply forgotten to assign to the correct milestone in the past.

[Martin Sjölund]

Removing the pre1.9.4 milestone in favor of 1.9.4.