fix header value parsing behavior for folded lines and make header va…

…lues always be arrays (of strings)

README.md

@@ -151,7 +151,7 @@ Methods
 
 * **prev**(< _function_ >callback) - _(void)_ - Attempts to move to the previous article in the current newsgroup. `callback` has 3 parameters: < _Error_ >err, < _integer_ >articleNum, < _string_ >msgID.
 
-* **headers**([< _string_ >which, ]< _function_ >callback) - _(void)_ - Retrieves the headers of the current article if `which` is not given or for the article whose number or message ID is `what`. `callback` has 4 parameters: < _Error_ >err, < _integer_ >articleNum, < _string_ >msgID, < _object_ >headers. `headers` values containing an Array stores duplicate header values.
+* **headers**([< _string_ >which, ]< _function_ >callback) - _(void)_ - Retrieves the headers of the current article if `which` is not given or for the article whose number or message ID is `what`. `callback` has 4 parameters: < _Error_ >err, < _integer_ >articleNum, < _string_ >msgID, < _object_ >headers. `headers` values are always arrays (of strings).
 
 * **body**([< _string_ >which, ]< _function_ >callback) - _(void)_ - Retrieves the body of the current article if `which` is not given or for the article whose number or message ID is `what`. `callback` has 4 parameters: < _Error_ >err, < _integer_ >articleNum, < _string_ >msgID, < _string_ >body. `body` is a binary string.
 

lib/nntp.js

@@ -15,7 +15,6 @@ var tls = require('tls'),
     reStat = /^(\d+)\s+(.+)$/,
     reGroup = /^(\d+)\s+(\d+)\s+(\d+)\s/,
     reHdr = /^([^:]+):\s?(.+)?$/,
-    reHdrFold = /^\s+(.+)$/,
     respsML = [100, 101, 215, 220, 221, 222, 224, 225, 230, 231],
     respsHaveArgs = [111, 211, 220, 221, 222, 223, 401],
     bytesCRLF = new Buffer([13, 10]),
@@ -382,19 +381,15 @@ NNTP.prototype.headers = function(what, cb) {
         continue;
       if (list[i][0] === '\t' || list[i][0] === ' ') {
         // folded header content
-        m = reHdrFold.exec(list[i]);
-        if (Array.isArray(headers[h]))
-          headers[h][headers[h].length - 1] += m[1];
-        else
-          headers[h] += m[1];
+        // RFC2822 says to just remove the CRLF and not the whitespace following
+        // it, so we follow the RFC and include the leading whitespace ...
+        headers[h][headers[h].length - 1] += m[1];
       } else {
         m = reHdr.exec(list[i]);
         h = m[1].toLowerCase();
         if (m[2]) {
           if (headers[h] === undefined)
-            headers[h] = m[2];
-          else if (!Array.isArray(headers[h]))
-            headers[h] = [headers[h], m[2]];
+            headers[h] = [m[2]];
           else
             headers[h].push(m[2]);
         } else