Strange su - behavior

[Clyde E. Kunkel]

Anyone know why in rawhide the following occurs (doesn't if I use sudo):

$ su -
Password:
grep: unrecognized option `--color=auto'
BusyBox v1.15.1 (2010-05-05 10:58:54 UTC) multi-call binary

Usage: grep [-HhrilLnqvsoweFEABCz] PATTERN [FILE]...

Search for PATTERN in each FILE or standard input

Options:
	-H	Prefix output lines with filename where match was found
	-h	Suppress the prefixing filename on output
	-r	Recurse subdirectories
	-i	Ignore case distinctions
	-l	List names of files that match
	-L	List names of files that do not match
	-n	Print line number with output lines
	-q	Quiet. Return 0 if PATTERN is found, 1 otherwise
	-v	Select non-matching lines
	-s	Suppress file open/read error messages
	-c	Only print count of matching lines
	-o	Show only the part of a line that matches PATTERN
	-m MAX	Match up to MAX times per file
	-w	Match whole words only
	-F	PATTERN is a set of newline-separated strings
	-E	PATTERN is an extended regular expression
	-e PTRN	Pattern to match
	-f FILE	Read pattern from file
	-A	Print NUM lines of trailing context
	-B	Print NUM lines of leading context
	-C	Print NUM lines of output context
	-z	Input is NUL terminated

[root at P5K-EWIFI ~]#


TIA