keychain: define SHORT_HOST if not defined
Fixes problems when using the plugin via antibody or antigen.
Diff
1diff --git a/plugins/keychain/keychain.plugin.zsh b/plugins/keychain/keychain.plugin.zsh
2index def97d8d1fff7e442ef9b9cb6d0b9f428b840104..1babf5a309a7283040ce354088c8537a454520e8 100644
3--- a/plugins/keychain/keychain.plugin.zsh
4+++ b/plugins/keychain/keychain.plugin.zsh
5@@ -1,3 +1,6 @@
6+# Define SHORT_HOST if not defined (%m = host name up to first .)
7+SHORT_HOST=${SHORT_HOST:-${(%):-%m}}
8+
9 function _start_agent() {
10 local agents
11 local -a identities