Using Robot Framework 2.0.4 (Python 2.6 on linux2)

We have a global variable @{gl}. Let's assume, that this variable already 
has some contents, for example [ This | is | a | list ]. Now we have some 
user keyword, which returns a list (but for demonstration, we can as well 
use the builtin "Create List"). We want to assign the result of the 
keyword to the global variable, hence we have to set a local list variable 
first. If the local variable is an empty list, then "Set Global Variable" 
has no effect. See good example:

| Set Global Variable | \@{gl}      | This | is | a | list |
| @{l}=               | Create List | Short|List|   |      |
| Set Global Variable | \@{gl}      | @{l} |    |   |      |

Okay, @{gl} is set to the contents of @{l}.

Bad example:

| Set Global Variable | \@{gl}      | This | is | a | list |
| @{l}=               | Create List |      |    |   |      |
| Set Global Variable | \@{gl}      | @{l} |    |   |      |

FAULT: @{gl} remains unchanged ! "Set Global Variable" keyword apparently 
interprets the empy list @{l} as "less than nothing", which means it 
doesn't do anything!

If we set @{l} to ${EMPTY}, the @{gl} is changed, but the @{l} and 
afterwards @{gl} is not an empty list, but a list containing one empty 
element, which is a difference (for example to the "Log Many" keyword).

Another strange thing: "Set Variable" keyword can assign lists, but raises 
an error in case of an empty list. Example:

| @{l}=     | Set Variable |     |     |

results in error "Cannot assign return value of keyword 'BuiltIn.Set 
Variable' to variable '@{l}': Expected list, got string instead", which is 
quite nonsense. In particular, if the empty list to assign is another 
variable, for example:

| @{empty_list}=   | Create List  |               |      |
| @{l}=            | Set Variable | @{empty_list} |      |


Imagine in the above example, that instead "Create List" we have a user 
keyword, which may return an empty or non-empty list, depending on time of 
day, for instance.