net.box: fix fetching of schema of an old version

After 2.2.0-633-gaa0964ae1 ('net.box: fix schema fetching from 1.10/2.1
servers') net.box expects that _vcollation system view exists on a
tarantool server of 2.2.1+ version. This is however not always so: a
server may be run on a new version of tarantool, but work on a schema of
an old version.

The situation with non last schema is usual for replication cluster in
process of upgrading: all instances run on the new version of tarantool
first (no auto-upgrade is performed by tarantools in a cluster). Then
box.schema.upgrade() should be called, but the instances should be
operable even before the call.

Before the commit net.box was unable to connect a server if it is run on
a schema without _vcollation system view (say, 2.1.3), but the server
executable is of 2.2.1 version or newer.

Note: I trim tests from the commit to polish them a bit more, but
include the fix itself to 2.4.1 release.

Follows up #4307
Fixes #4691

src/box/lua/net_box.lua

@@ -56,6 +56,7 @@ local E_UNKNOWN              = box.error.UNKNOWN
 local E_NO_CONNECTION        = box.error.NO_CONNECTION
 local E_TIMEOUT              = box.error.TIMEOUT
 local E_PROC_LUA             = box.error.PROC_LUA
+local E_NO_SUCH_SPACE        = box.error.NO_SUCH_SPACE
 
 -- utility tables
 local is_final_state         = {closed = 1, error = 1}
@@ -803,6 +804,13 @@ local function create_transport(host, port, user, password, callback,
                 local status = hdr[IPROTO_STATUS_KEY]
                 local response_schema_version = hdr[IPROTO_SCHEMA_VERSION_KEY]
                 if status ~= 0 then
+                    -- No _vcollation space (server has an old
+                    -- schema version).
+                    local errno = band(status, IPROTO_ERRNO_MASK)
+                    if id == select3_id and errno == E_NO_SUCH_SPACE then
+                        peer_has_vcollation = false
+                        goto continue
+                    end
                     local body
                     body, body_end = decode(body_rpos)
                     return error_sm(E_NO_CONNECTION, body[IPROTO_ERROR_KEY])
@@ -817,6 +825,7 @@ local function create_transport(host, port, user, password, callback,
                 body, body_end = decode(body_rpos)
                 response[id] = body[IPROTO_DATA_KEY]
             end
+            ::continue::
         until response[select1_id] and response[select2_id] and
               (not peer_has_vcollation or response[select3_id])
         -- trick: response[select3_id] is nil when the key is nil