more env_keep suggestions from debian

This is what Debian has in its default sudoers. This has grown from
decades of processing Debian bug reports. Feel free to accept some of
them.

Author: Marc Haber

plugins/sudoers/sudoers.in

@@ -84,6 +84,25 @@ Defaults!@visudo@ env_keep += "SUDO_EDITOR EDITOR VISUAL"
 ## equivalent users (group sudo)
 # Defaults:%sudo env_keep += "http_proxy https_proxy ftp_proxy all_proxy no_proxy"
 ##
+## Uncomment to preserve environment variables for grep
+# Defaults:%sudo env_keep += "GREP_COLOR"
+##
+## Uncomment to preserve git related environment. While you shouldn't
+## normally run git as root, you need to with etckeeper
+# Defaults:%sudo env_keep += "GIT_AUTHOR_* GIT_COMMITTER_*"
+##
+## Uncomment to preserve Debian-related environment variables. root 
+## won't have sensible values for them.
+# Defaults:%sudo env_keep += "EMAIL DEBEMAIL DEBFULLNAME"
+##
+## Uncomment to allow root to use the calling user's ssh agent
+## transparently. This enabled "sudo scp" or "sudo rsync"
+# Defaults:%sudo env_keep += "SSH_AGENT_PID SSH_AUTH_SOCK"
+##
+## Uncomment to allow root to use the calling user's gpg agent
+## transparently. This enabled "sudo scp" or "sudo rsync"
+# Defaults:%sudo env_keep += "GPG_AGENT_INFO"
+##
 ## Uncomment to disable "use_pty" when running commands as root.
 ## Commands run as non-root users will run in a pseudo-terminal,
 ## not the user's own terminal, to prevent command injection.