Please answer these questions before submitting your issue. Thanks!

1. What version of Go are you using (go version)?

   go version go1.6.2 darwin/amd64

2. What operating system and processor architecture are you using (go env)?

   GOARCH="amd64"
   GOBIN="/Users/simon/go/bin"
   GOEXE=""
   GOHOSTARCH="amd64"
   GOHOSTOS="darwin"
   GOOS="darwin"
   GOPATH="/Users/simon/Myfruit/Go/imports:/Users/simon/Mygo"
   GORACE=""
   GOROOT="/Users/simon/go"
   GOTOOLDIR="/Users/simon/go/pkg/tool/darwin_amd64"
   GO15VENDOREXPERIMENT="1"
   CC="clang"
   GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fno-common"
   CXX="clang++"
   CGO_ENABLED="1"
   

3. What did you do?
   If possible, provide a recipe for reproducing the error.
   A complete runnable program is good.
   A link on play.golang.org is best.

code: https://play.golang.org/p/kjL-dBzhI5

according to rfc1421 4.4 Encapsulation Mechanism, the key is in invaild format

when I run the command openssl rsa -noout -text -in test.key, the following error occurred:

unable to load Private Key
10374:error:0906D066:PEM routines:PEM_read_bio:bad end line:/SourceCache/OpenSSL098/OpenSSL098-50/src/crypto/pem/pem_lib.c:747:

similar issue goes here:
http://stackoverflow.com/questions/18460035/unable-to-load-private-key-pem-routinespem-read-biono-start-linepem-lib-c6

1. What did you expect to see?

output message: fail to decode the key

1. What did you see instead?

output message: success to decode the key

maybe the following patch help

diff --git a/src/encoding/pem/pem.go b/src/encoding/pem/pem.go
index 506196b..b00d504 100644
--- a/src/encoding/pem/pem.go
+++ b/src/encoding/pem/pem.go
@@ -132,6 +132,11 @@ func Decode(data []byte) (p *Block, rest []byte) {
                return decodeError(data, rest)
        }

+       endLine, next := getline(rest[endIndex:])
+       if !bytes.HasSuffix(endLine, pemEndOfLine) {
+               return decodeError(data, next)
+       }
+
        base64Data := removeWhitespace(rest[:endIndex])
        p.Bytes = make([]byte, base64.StdEncoding.DecodedLen(len(base64Data)))
        n, err := base64.StdEncoding.Decode(p.Bytes, base64Data)