Handle nested subvolumes & remove broken git exclusion

src/borg-common.sh

@@ -2,6 +2,27 @@
 
 export BORG_RSH='ssh -oBatchMode=yes'
 
+# Borg expands placeholders in both names and archive filters. Only the filter
+# needs glob escaping; user-supplied prefixes are literal in both places.
+borg_literal_prefix() {
+    local mode=$1 prefix=$2 character index
+    for ((index = 0; index < ${#prefix}; index++)); do
+        character=${prefix:index:1}
+        case "$character" in
+            '{') printf '{{' ;;
+            '}') printf '}}' ;;
+            '['|'?'|'*')
+                if [[ $mode == glob ]]; then
+                    printf '[%s]' "$character"
+                else
+                    printf '%s' "$character"
+                fi
+                ;;
+            *) printf '%s' "$character" ;;
+        esac
+    done
+}
+
 # Never break another client's repository/cache lock. Borg 1.4 only accepts
 # finite waits, so retry lock timeouts forever; other errors must propagate.
 borg_wait() {