sed: fix zero chars match/replace

function                                             old     new   delta
process_files                                       2099    2181     +82

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

testsuite/sed.tests

@@ -52,10 +52,8 @@ testing "sed with empty match" "sed 's/z*//g'" "string\n" "" "string\n"
 testing "sed s//p" "sed -e s/foo/bar/p -e s/bar/baz/p" "bar\nbaz\nbaz\n" \
 	"" "foo\n"
 testing "sed -n s//p" "sed -ne s/abc/def/p" "def\n" "" "abc\n"
-test x"$SKIP_KNOWN_BUGS" = x"" && {
 testing "sed s//g (exhaustive)" "sed -e 's/[[:space:]]*/,/g'" ",1,2,3,4,5,\n" \
 	"" "12345\n"
-}
 testing "sed s arbitrary delimiter" "sed -e 's woo boing '" "boing\n" "" "woo\n"
 testing "sed s chains" "sed -e s/foo/bar/ -e s/bar/baz/" "baz\n" "" "foo\n"
 testing "sed s chains2" "sed -e s/foo/bar/ -e s/baz/nee/" "bar\n" "" "foo\n"
@@ -296,6 +294,14 @@ testing "sed -i finishes ranges correctly" \
 	"sed '1,2d' -i input; echo \$?; cat input" \
 	"0\n3\n4\n" "1\n2\n3\n4\n" ""
 
+testing "sed zero chars match/replace advances correctly 1" \
+	"sed 's/l*/@/g'" \
+	"@h@e@o@\n" "" "helllo\n"
+
+testing "sed zero chars match/replace advances correctly 2" \
+	"sed 's [^ .]* x g'" \
+	"x x.x\n" "" " a.b\n"
+
 # testing "description" "commands" "result" "infile" "stdin"
 
 exit $FAILCOUNT