bufio: UnreadByte can unread more than one byte

[rui314]

What does 'go version' print?
go version devel +2b85dda01af0 Wed Mar 19 10:14:04 2014 -0700 linux/amd64

What steps reproduce the problem?
http://play.golang.org/p/S97IegN_jI

UnreadByte can be called any number of times without error until it reaches beginning of
the internal buffer, despite it's documentation says "only the most recently read
byte can be unread."

I'm not sure if it's an undefined behavior or a bug, so I'm just filing it.

[griesemer]

Comment 1:

Labels changed: added release-go1.3maybe, repo-main.

Owner changed to @griesemer.

Status changed to Accepted.

[griesemer]

Comment 2:

The documentation should say that only unreading of the most recently read byte is
guaranteed. That said, exactly when it's possible to unread more bytes depends on a
various factors and is not easily predictable in general. Changed code to follow the
documentation and added test:
https://golang.org/cl/86180043/

Status changed to Started.

[gopherbot]

Comment 3:

CL https://golang.org/cl/86180043 mentions this issue.

[griesemer]

Comment 4:

This issue was closed by revision 8bd9242.

Status changed to Fixed.