Verify only once test harness sftp server connectivity and functionality.

Make sure that the sftp client tool uses the ssh client binary that we have
used to generate the configuration files, otherwise sftp might be using one
located in the preferred path compiled into sftp.

tests/runtests.pl

@@ -702,9 +702,15 @@ sub verifysftp {
         logmsg "RUN: SFTP server cannot find $sftpexe\n";
         return -1;
     }
+    # Find out ssh client canonical file name
+    my $ssh = find_ssh();
+    if(!$ssh) {
+        logmsg "RUN: SFTP server cannot find $sshexe\n";
+        return -1;
+    }
     # Connect to sftp server, authenticate and run a remote pwd
     # command using our generated configuration and key files
-    my $cmd = "$sftp -b $sftpcmds -F $sftpconfig $ip > $sftplog 2>&1";
+    my $cmd = "$sftp -b $sftpcmds -F $sftpconfig -S $ssh $ip > $sftplog 2>&1";
     my $res = runclient($cmd);
     # Search for pwd command response in log file
     if(open(SFTPLOGFILE, "<$sftplog")) {
@@ -756,7 +762,6 @@ my %protofunc = ('http' => \&verifyhttp,
                  'ftps' => \&verifyftp,
                  'tftp' => \&verifyftp,
                  'ssh' => \&verifyssh,
-                 'sftp' => \&verifysftp,
                  'socks' => \&verifysocks);
 
 sub verifyserver {
@@ -1179,9 +1184,9 @@ sub runsshserver {
 
     # once it is known that the ssh server is alive, sftp server verification
     # is performed actually connecting to it, authenticating and performing a
-    # very simple remote command.
+    # very simple remote command.  This verification is tried only one time.
 
-    if(!verifyserver("sftp",$ip,$port)) {
+    if(verifysftp("sftp",$ip,$port) < 1) {
         logmsg "RUN: SFTP server failed verification\n";
         # failed to talk to it properly. Kill the server and return failure
         display_sftplog();