grep -F: regex error when pattern includes '/'

[mknos]

• grep -F is not supposed to use regex at all, but in the perl version it does
• I have a file "01" containing the pattern 'a/b' on line 3
• System grep (gnu) has no problem searching for this pattern, but perl grep chokes
• From the error it appears the '/b' part of the pattern is terminating a regex

%grep -Fn  'a/b' 01 
3: /test/a/b/c
%perl grep -Fn  'a/b' 01 
Unknown regexp modifier "/b" at (eval 1) line 1, at end of line
syntax error at (eval 1) line 1, at EOF
	...propagated at grep line 261.