Use FS_CHMOD_FILE rather than an explicit 0644 in copy_dir() and _copy_dir().

This occurs when we can't copy a file. We chmod it and try again.

see #22704.

Built from https://develop.svn.wordpress.org/trunk@25793


git-svn-id: http://core.svn.wordpress.org/trunk@25705 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Core Updates: Verify that all files we're about to copy are actually writable, when using the direct transport.

Once we begin to copy core files, all bets are off. This allows us to fail early when we'll otherwise need to stop midway through due to permissions issues, which is a particularly bad problem when only some files have permissions issues.

see #22704.

Built from https://develop.svn.wordpress.org/trunk@25794


git-svn-id: http://core.svn.wordpress.org/trunk@25706 1a063a9b-81f0-0310-95a4-ce76da25c4cd
3.7-beta2-25795

Built from https://develop.svn.wordpress.org/trunk@25795


git-svn-id: http://core.svn.wordpress.org/trunk@25707 1a063a9b-81f0-0310-95a4-ce76da25c4cd
In show_message(), only print error data if it is a string.

see #25576, [25775].

Built from https://develop.svn.wordpress.org/trunk@25796


git-svn-id: http://core.svn.wordpress.org/trunk@25708 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Only add error data to the files_not_writable WP_Error if the install already has [25775] and [25796] applied.

see #22704.

Built from https://develop.svn.wordpress.org/trunk@25797


git-svn-id: http://core.svn.wordpress.org/trunk@25709 1a063a9b-81f0-0310-95a4-ce76da25c4cd