[gparted] Only execute mkudffs during detection when it is known to exist (#786050)

[Curtis Gedak <gedakc src gnome org>]

commit c353630312bb05c53ff4221bff6b2cbad58a6ca3
Author: Mike Fleetwood <mike fleetwood googlemail com>
Date:   Tue Aug 8 20:30:23 2017 +0100

    Only execute mkudffs during detection when it is known to exist (#786050)
    
    When udftools are not installed and the mkudffs program isn't found
    GParted would report this error during startup:
    
        # ./gpartedbin
        ======================
        libparted : 3.1
        ======================
        Failed to execute child process "mkudffs" (No such file or directory)
    
    Only run mkudffs to check for an old version when the program is found.
    
    Bug 786050 - GParted reports failed to execute child process "mkudffs"
                 when it is not installed

 src/udf.cc |    9 +++++----
 1 files changed, 5 insertions(+), 4 deletions(-)
---
diff --git a/src/udf.cc b/src/udf.cc
index c0ee8db..6884f9e 100644
--- a/src/udf.cc
+++ b/src/udf.cc
@@ -41,15 +41,16 @@ FS udf::get_filesystem_support()
        fs.MIN = MIN_UDF_BLOCKS * MIN_UDF_BLOCKSIZE;
        fs.MAX = MAX_UDF_BLOCKS * MAX_UDF_BLOCKSIZE;
 
+       old_mkudffs = false;
        if ( ! Glib::find_program_in_path( "mkudffs" ).empty() )
        {
                fs.create = FS::EXTERNAL;
                fs.create_with_label = FS::EXTERNAL;
-       }
 
-       // Detect old mkudffs prior to version 1.1 by lack of --label option.
-       Utils::execute_command( "mkudffs --help", output, error, true );
-       old_mkudffs = Utils::regexp_label( output + error, "--label" ).empty();
+               // Detect old mkudffs prior to version 1.1 by lack of --label option.
+               Utils::execute_command( "mkudffs --help", output, error, true );
+               old_mkudffs = Utils::regexp_label( output + error, "--label" ).empty();
+       }
 
        // NOTE: Other external programs do not exist yet