#74 Avoid delete of cached plaintext objects on upgrading

When the user is upgrading their transcrypt we don't need to do the
extra work of deleting cached plaintext objects as part of the
uninstall step, because the repo is about to be re-inited anyway.

Author: jmurty

transcrypt

@@ -581,7 +581,9 @@ uninstall_transcrypt() {
 	if [[ $answer =~ $YES_REGEX ]]; then
 		clean_gitconfig
 
-		remove_cached_plaintext
+		if [[ ! $upgrade ]]; then
+			remove_cached_plaintext
+		fi
 
 		# remove helper scripts
 		for script in {clean,smudge,textconv,merge}; do