cog-prt-atomspace doesn't work in union of two atomspaces

[sikefield3]

In the context of #15 , while testing the Multiframe-Example
following happened:
When I tried to connect the union atomspace to a RocksDB and then try cog-prt-atomspace, I got a segfault.:

(cog-set-atomspace! c)
(define rsn (RocksStorageNode "rocks:///home/opcwdir/repodock/ForTestingStuff/foo.rdb"))
(cog-open rsn)
(store-atomspace)
(cog-prt-atomspace)

This happens also, if I use cog-rocks-open.
Printing the content with cog-rocks-print works fine.

Not sure, if this is a realistic use case.

[linas]

OK, I can reproduce this with the following

(use-modules (opencog) (opencog exec))
(use-modules (opencog persist))
(use-modules (opencog persist-rocks))

(define a (AtomSpace))
(define b (AtomSpace))
(define c (AtomSpace a b))

(cog-set-atomspace! a)
(Concept "I'm in A")
(cog-prt-atomspace)

(cog-set-atomspace! b)
(Concept "I'm in B")
(cog-prt-atomspace)

(cog-set-atomspace! c)
(define rsn (RocksStorageNode "rocks:///tmp/foo"))
(cog-open rsn)
(store-atomspace)
(cog-prt-atomspace)

[linas]

Fixed the crash, here:

opencog/atomspace#3037

[linas]

Added unit test in 4499f34

Closing; there's a fix, and a unit test for it. Thanks for the report!

[linas]

FWIW, I did NOT test beyond the above! There may still be bugs, weirdness, or unexpected behavior! The frame stuff is relatively new, and hasn't been hit hard by "real world" applications.