I did a little more investigation and it looks like information separators have been included in whitespace since unicode type was first implemented in Python:

guido 11967 Fri Mar 10 22:52:46 2000 +0000: /* Returns 1 for Unicode characters having the type 'WS', 'B' or 'S',
guido 11967 Fri Mar 10 22:52:46 2000 +0000:    0 otherwise. */
guido 11967 Fri Mar 10 22:52:46 2000 +0000:
guido 11967 Fri Mar 10 22:52:46 2000 +0000: int _PyUnicode_IsWhitespace(register const Py_UNICODE ch)
guido 11967 Fri Mar 10 22:52:46 2000 +0000: {
guido 11967 Fri Mar 10 22:52:46 2000 +0000:     switch (ch) {
guido 11967 Fri Mar 10 22:52:46 2000 +0000:     case 0x0009: /* HORIZONTAL TABULATION */
guido 11967 Fri Mar 10 22:52:46 2000 +0000:     case 0x000A: /* LINE FEED */
guido 11967 Fri Mar 10 22:52:46 2000 +0000:     case 0x000B: /* VERTICAL TABULATION */
guido 11967 Fri Mar 10 22:52:46 2000 +0000:     case 0x000C: /* FORM FEED */
guido 11967 Fri Mar 10 22:52:46 2000 +0000:     case 0x000D: /* CARRIAGE RETURN */
guido 11967 Fri Mar 10 22:52:46 2000 +0000:     case 0x001C: /* FILE SEPARATOR */
guido 11967 Fri Mar 10 22:52:46 2000 +0000:     case 0x001D: /* GROUP SEPARATOR */
guido 11967 Fri Mar 10 22:52:46 2000 +0000:     case 0x001E: /* RECORD SEPARATOR */
guido 11967 Fri Mar 10 22:52:46 2000 +0000:     case 0x001F: /* UNIT SEPARATOR */
guido 11967 Fri Mar 10 22:52:46 2000 +0000:     case 0x0020: /* SPACE */
guido 11967 Fri Mar 10 22:52:46 2000 +0000:     case 0x1680: /* OGHAM SPACE MARK */
guido 11967 Fri Mar 10 22:52:46 2000 +0000:     case 0x2000: /* EN QUAD */
guido 11967 Fri Mar 10 22:52:46 2000 +0000:     case 0x2001: /* EM QUAD */
guido 11967 Fri Mar 10 22:52:46 2000 +0000:     case 0x2002: /* EN SPACE */
guido 11967 Fri Mar 10 22:52:46 2000 +0000:     case 0x2003: /* EM SPACE */
guido 11967 Fri Mar 10 22:52:46 2000 +0000:     case 0x2004: /* THREE-PER-EM SPACE */
guido 11967 Fri Mar 10 22:52:46 2000 +0000:     case 0x2005: /* FOUR-PER-EM SPACE */
guido 11967 Fri Mar 10 22:52:46 2000 +0000:     case 0x2006: /* SIX-PER-EM SPACE */
guido 11967 Fri Mar 10 22:52:46 2000 +0000:     case 0x2007: /* FIGURE SPACE */
guido 11967 Fri Mar 10 22:52:46 2000 +0000:     case 0x2008: /* PUNCTUATION SPACE */
guido 11967 Fri Mar 10 22:52:46 2000 +0000:     case 0x2009: /* THIN SPACE */
guido 11967 Fri Mar 10 22:52:46 2000 +0000:     case 0x200A: /* HAIR SPACE */
guido 11967 Fri Mar 10 22:52:46 2000 +0000:     case 0x2028: /* LINE SEPARATOR */
guido 11967 Fri Mar 10 22:52:46 2000 +0000:     case 0x202F: /* NARROW NO-BREAK SPACE */
guido 11967 Fri Mar 10 22:52:46 2000 +0000:     case 0x3000: /* IDEOGRAPHIC SPACE */
guido 11967 Fri Mar 10 22:52:46 2000 +0000:     return 1;
guido 11967 Fri Mar 10 22:52:46 2000 +0000:     default:
guido 11967 Fri Mar 10 22:52:46 2000 +0000:     return 0;
guido 11967 Fri Mar 10 22:52:46 2000 +0000:     }
guido 11967 Fri Mar 10 22:52:46 2000 +0000: }
guido 11967 Fri Mar 10 22:52:46 2000 +0000:

(hg blame -u -d -n -r 11967 Objects/unicodectype.c)