git: Add pre-push hook for catching accidental versions

pre-push.sh

@@ -0,0 +1,11 @@
+#!/bin/bash
+
+# A pre-push hook to prevent accidentally pushing new major versions.
+
+vs="$(git tag | sort -rV | cut -c 1,2 | head -n 2)"
+if [[ "$(echo "$vs" | wc -l | awk '{print $1}')" == "2" ]] && [[ -z $(echo "$vs" | uniq -d) ]]; then
+    echo >&2 "It looks like you're pushing a tag with a new major version!"
+    echo >&2 "...I'm gonna assume that was a mistake."
+    echo >&2 "If it wasn't, just rm this hook before pushing again."
+    exit 1;
+fi