Remove pt conf files before running Jenkins test else they can cause weird results. Make pt-stalk --collect run-time test more liberal.

sandbox/jenkins-test

@@ -59,6 +59,12 @@ export PERCONA_TOOLKIT_SANDBOX="$MYSQL_BASE_DIR"
 export PATH="$PATH:/usr/sbin:$MYSQL_BASE_DIR/bin"
 export LANG="en_US.UTF-8"
 
+# ######################################### #
+# Remove conf files that's shouldn't exist. #
+# ######################################### #
+rm ~/.pt-*conf*
+rm ~/.my*
+
 #############################
 # Check and start test env. #
 #############################

t/pt-stalk/pt-stalk.t

@@ -149,9 +149,9 @@ like(
 # the samples may not be precisely 1 second apart.
 chomp($output = `cat $dest/*-df | grep -c '^TS'`);
 ok(
-   $output >= 1 && $output <= 2,
+   $output >= 1 && $output <= 3,
    "Collect ran for --run-time"
-);
+) or diag("Run time: $output");
 
 ok(
    PerconaTest::not_running("pt-stalk --iterations 1"),