Sticky escape with module switch

[xdelaruelle]

Sticky or super-sticky modules can be escaped with module switch when switch-on module cannot be found. This is an issue as such sticky module should not be able to unload.

$ find modulefiles/foo
modulefiles/foo
modulefiles/foo/.modulerc
modulefiles/foo/1.0
$ cat modulefiles/foo/.modulerc 
#%Module
module-tag sticky foo
$ module use ./modulefiles
$ module load foo
$ module switch foo/2.0
Switching from foo/1.0 to foo/2.0
  ERROR: Unable to locate a modulefile for 'foo/2.0'
$ module list
No Modulefiles Currently Loaded.

In this example, foo/1.0 should stay loaded as it is tagged sticky.

Switch-on module should be checked before unloading sticky module to verify if an equivalent sticky module can be loaded.