Cluster test: less console-spammy resharding test.

tests/cluster/tests/04-resharding.tcl

@@ -53,13 +53,16 @@ test "Cluster consistency during live resharding" {
             puts -nonewline "...Starting resharding..."
             flush stdout
             set target [dict get [get_myself [randomInt 5]] id]
-            set tribpid [exec \
+            set tribpid [lindex [exec \
                 ../../../src/redis-trib.rb reshard \
                 --from all \
                 --to $target \
                 --slots 100 \
                 --yes \
-                127.0.0.1:[get_instance_attrib redis 0 port] &]
+                127.0.0.1:[get_instance_attrib redis 0 port] \
+                | [info nameofexecutable] \
+                ../tests/helpers/onlydots.tcl \
+                &] 0]
         }
 
         # Write random data to random list.

tests/cluster/tests/helpers/onlydots.tcl

@@ -0,0 +1,14 @@
+# Read the standard input and only shows dots in the output, filtering out
+# all the other characters. Designed to avoid bufferization so that when
+# we get the output of redis-trib and want to show just the dots, we'll see
+# the dots as soon as redis-trib will output them.
+
+fconfigure stdin -buffering none
+
+while 1 {
+    set c [read stdin 1]
+    if {$c eq {.}} {
+        puts -nonewline .
+        flush stdout
+    }
+}