Harish Fulara authored Feb 22, 2018 and Alexandru Băluț committed Feb 21, 2018

How copy-paste works? The object (o_copy) returned by the copy function
stores reference to the object (o_orig) whose copy is made. While
pasting o_copy onto the timeline, this reference is used to set the
timeline for o_copy, i.e., timeline(o_copy) = timeline(o_orig), which
makes o_copy get pasted on the timeline.

Issue with previous logic? We were saving a copy of 'self.__copiedGroup'
before pasting it onto the timeline and then restoring
'self.__copiedGroup' from previously saved copy after the paste
operation is done (for the first time). This saving and restoring
'self.__copiedGroup' would make it store a reference to itself. When we
paste again (for the second time) on the timeline, no timeline would be
associated with the pasted object because 'self.__copiedGroup' refers to
itself and there is no timeline associated with 'self.__copiedGroup'.
Hence, nothing would get pasted onto the timeline.

Fixes https://phabricator.freedesktop.org/T7639