Description:
------------
Using a text editor (Eclipse) for PHP the attached code will not work properly when a tab is typed inside of the ob_start() section.  No errors are reported but when the HTML email is received it is represented as raw text including the header data.  Debugging for this in such case can be very very difficult.

Reproduce code:
---------------
function test_html_email(){
$to = 'jason.anderson@abcphones.com';
$subject = 'My Code';
$random_hash = md5(date('r', time()));
$headers = "From: admin@pgxgolf.com\r\nReply-To: admin@pgxgolf.com";
$headers .= "\r\nContent-Type: multipart/alternative; boundary=\"PHP-alt-".$random_hash."\"";
ob_start(); //Turn on output buffering  - Notice tabs below
?>      --PHP-alt-<?php echo $random_hash; ?> 
	Content-Type: text/plain; charset="iso-8859-1"
	Content-Transfer-Encoding: 7bit
	
	Hello World!!! 
	This is simple text email message.
	
	--PHP-alt-<?php echo $random_hash; ?> 
	Content-Type: text/html; charset="iso-8859-1"
	Content-Transfer-Encoding: 7bit
	
	<h2>Hello World!</h2>
	<p>This is something with <b>HTML</b> formatting.</p>
	
	--PHP-alt-<?php echo $random_hash; ?>--
<?php $message = ob_get_clean();
ob_end_flush();
$mail_sent = @mail( $to, $subject, $message, $headers );
echo $mail_sent ? "Mail sent" : "Mail failed";
}
test_html_email();

Expected result:
----------------
Hello World!
This is something with HTML formatting.


Actual result:
--------------
--PHP-alt-527d2deecd08a0f3e80bced5cace8aaa 
	Content-Type: text/plain; charset="iso-8859-1"
	Content-Transfer-Encoding: 7bit
	
	Hello World!!! 
	This is simple text email message.
	
	--PHP-alt-527d2deecd08a0f3e80bced5cace8aaa 
	Content-Type: text/html; charset="iso-8859-1"
	Content-Transfer-Encoding: 7bit
	
	<h2>Hello World!</h2>
	<p>This is something with <b>HTML</b> formatting.</p>
	
	--PHP-alt-527d2deecd08a0f3e80bced5cace8aaa--