[borg] add init option to allow skipping init command

In some cases it may be desirable to skip repository initialization, for
example when the repository is located at the root of a mount point.

examples/example.borg

@@ -35,6 +35,12 @@
 
 [source]
 
+## default is to initialize the backup repository if absent
+## set to no to skip this step
+##
+## Default:
+# init = yes
+
 ## how many hours, days, weeks and months of data to keep
 ##
 ## for more info see : borg help prune

handlers/borg.in

@@ -23,6 +23,7 @@ getconf nicelevel 0
 getconf bwlimit
 
 setsection source
+getconf init yes
 getconf prune yes
 getconf keephourly 1
 getconf keepdaily 7
@@ -82,10 +83,9 @@ fi
 
 ### INIT IF NEEDED ###
 
+if [ "$init" == "yes" ]; then
    initstr="borg init --encryption=$encryption $execstr_repository"
-
    debug "$initstr"
-
    if [ $test = 0 ]; then
       output="`su -c "$initstr" 2>&1`"
       if [ $? = 2 ]; then
@@ -96,6 +96,7 @@ if [ $test = 0 ]; then
          warning "Repository has been initialized"
       fi
    fi
+fi
 
 ### EXECUTE ###