crypto/openpgp: fixed dangerous use of for loop variable
crypto/openpgp: fixed dangerous use of for loop variable

In function readSignedMessage a pointer to for loop variable 'key' was incorrectly being assigned
to md.SignedBy. Changed so that md.SignedBy is pointing to the 'more correct' memory position.

R=golang-dev, r, agl
CC=golang-dev
http://codereview.appspot.com/4631088

Committer: Rob Pike <4dc7c9ec434ed06502767136789763ec11d2c4b7@golang.org>

h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang