csv: fix issue 2366 - overly aggressive TrimLeadingSpace

Address the issue coalescing two records together when TrimLeadingSpace
is set to true.

The input

        a,b,
        c,d,e

Would result with a singled a,b,c,d,e record.
With TrailingComma set to true it should give two records.
With TrailingComma set to false it should be an error.

Fixes #2366.

R=golang-dev, go.peter.90, r
CC=golang-dev
https://golang.org/cl/5284046

src/pkg/csv/reader.go

@@ -267,7 +267,7 @@ func (r *Reader) parseField() (haveField bool, delim int, err os.Error) {
 	}
 
 	if r.TrimLeadingSpace {
-		for unicode.IsSpace(rune) {
+		for rune != '\n' && unicode.IsSpace(rune) {
 			rune, err = r.readRune()
 			if err != nil {
 				return false, 0, err
@@ -355,7 +355,7 @@ func (r *Reader) parseField() (haveField bool, delim int, err os.Error) {
 		c := r.column
 		rune, err = r.readRune()
 		if r.TrimLeadingSpace {
-			for unicode.IsSpace(rune) {
+			for rune != '\n' && unicode.IsSpace(rune) {
 				rune, err = r.readRune()
 				if err != nil {
 					break

src/pkg/csv/reader_test.go

@@ -129,7 +129,6 @@ field"`,
 	{
 		Name:  "BadDoubleQuotes",
 		Input: `a""b,c`,
-		Output: [][]string{{`a""b`, `c`}},
 		Error: `bare " in non-quoted-field`, Line: 1, Column: 1,
 	},
 	{
@@ -231,6 +230,23 @@ x,,,
 			{"", "", "", ""},
 		},
 	},
+	{
+		Name:             "Issue 2366",
+		TrailingComma:    true,
+		TrimLeadingSpace: true,
+		Input:            "a,b,\nc,d,e",
+		Output: [][]string{
+			{"a", "b", ""},
+			{"c", "d", "e"},
+		},
+	},
+	{
+		Name:             "Issue 2366a",
+		TrailingComma:    false,
+		TrimLeadingSpace: true,
+		Input:            "a,b,\nc,d,e",
+		Error:            "extra delimiter at end of line",
+	},
 }
 
 func TestRead(t *testing.T) {