Scenario.timeseries() not working when using transact() or check_out()

[OFR-IIASA]

When a scenario object is checked out it is not possible to retrieve timeseries data.

Code sample or context

scen.check_out()
scen.timeseries()

or

with scen.transact():
    scen.timeseries()

Expected result

retrieve timeseries data; logic equivalent to that of parameters and/or sets.

Error message

*** at.ac.iiasa.ixmp.exceptions.at.ac.iiasa.ixmp.exceptions.IxException: at.ac.iiasa.ixmp.exceptions.IxException: This Scenario must be checked in before performing this operation!

[khaeru]

Added the 'bug' label and to the project tracker.

A minimal working example would help, here, as that could be more easily turned into a test.

[OFR-IIASA]

Executing the above lines of code on any given scenario should yield the error message above.