fix small test suite race conditions

tests/support/util.tcl

@@ -91,6 +91,14 @@ proc wait_for_sync r {
     }
 }
 
+proc wait_for_ofs_sync {r1 r2} {
+    wait_for_condition 50 100 {
+        [status $r1 master_repl_offset] eq [status $r2 master_repl_offset]
+    } else {
+        fail "replica didn't sync in time"
+    }
+}
+
 # Random integer between 0 and max (excluded).
 proc randomInt {max} {
     expr {int(rand()*$max)}

tests/unit/memefficiency.tcl

@@ -90,6 +90,7 @@ start_server {tags {"defrag"}} {
         test "Active defrag big keys" {
             r flushdb
             r config resetstat
+            r config set save "" ;# prevent bgsave from interfereing with save below
             r config set activedefrag no
             r config set active-defrag-max-scan-fields 1000
             r config set active-defrag-threshold-lower 5

tests/unit/type/stream-cgroups.tcl

@@ -144,6 +144,8 @@ start_server {
                     }
                 }
 
+                wait_for_ofs_sync $master $slave
+
                 # Turn slave into master
                 $slave slaveof no one