time: parse fractional second with single digit

Fixes #3487.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/6011050

src/pkg/time/format.go

@@ -714,7 +714,7 @@ func Parse(layout, value string) (Time, error) {
 			}
 			// Special case: do we have a fractional second but no
 			// fractional second in the format?
-			if len(value) > 2 && value[0] == '.' && isDigit(value, 1) {
+			if len(value) >= 2 && value[0] == '.' && isDigit(value, 1) {
 				_, std, _ := nextStdChunk(layout)
 				if len(std) > 0 && std[0] == '.' && isDigit(std, 1) {
 					// Fractional second in the layout; proceed normally

src/pkg/time/time_test.go

@@ -310,6 +310,7 @@ var parseTests = []ParseTest{
 	{"RFC1123", RFC1123, "Thu, 04 Feb 2010 21:00:57.01234 PST", true, true, 1, 5},
 	{"RFC1123Z", RFC1123Z, "Thu, 04 Feb 2010 21:00:57.01234 -0800", true, true, 1, 5},
 	{"RFC3339", RFC3339, "2010-02-04T21:00:57.012345678-08:00", true, false, 1, 9},
+	{"custom: \"2006-01-02 15:04:05\"", "2006-01-02 15:04:05", "2010-02-04 21:00:57.0", false, false, 1, 0},
 	// Amount of white space should not matter.
 	{"ANSIC", ANSIC, "Thu Feb 4 21:00:57 2010", false, true, 1, 0},
 	{"ANSIC", ANSIC, "Thu      Feb     4     21:00:57     2010", false, true, 1, 0},