BLOCK_OBSERVATION with source=summary cause ERT to segfault without a grid

[eivindsm]

I have managed to get a segfault by:
Configure ERT without a grid and with BLOCK_OBSERBATIONS with source=summary. Trace back indicates that ERT is trying to read the grid even though this is not necessary.

Abort called from: util_abort_signal (/var/jenkins/jenkinsbe/workspace/komodo/cache/libecl-2.2.8/lib/util/util.c:4959)

Error message: Program received signal:11

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#00 util_abort__(..) in ??:0
#1 ???(..) in sigaction.c:0
#2 ecl_grid_ijk_valid(..) in ??:0
#3 block_obs_alloc_complete(..) in ??:0
#4 obs_vector_alloc_from_BLOCK_OBSERVATION(..) in ??:0
#5 enkf_obs_load(..) in ??:0