github.com/cockroachdb/cockroach/pkg/ccl/importccl: _mismatch_cols failed under stress

[cockroach-teamcity]

SHA: https://github.com/cockroachdb/cockroach/commits/f818c4c3b946c40839921c72fc1322fb3b385ee6

Parameters:

TAGS=
GOFLAGS=-race

Failed test: https://teamcity.cockroachdb.com/viewLog.html?buildId=772409&tab=buildLog

=== RUN   TestImportData/PGDUMP:_mismatch_cols
I180711 06:32:20.857678 2923 ccl/importccl/read_import_proc.go:82  [import-distsql,n1] could not fetch file size; falling back to per-file progress: bad ContentLength: -1
I180711 06:32:21.063126 3009 storage/replica_command.go:275  [split,n1,s1,r47/1:/{Table/75-Max}] initiating a split of this range at key /Table/76 [r48]

[knz]

Dup #27360.

[knz]

Also #27498