dup: document how to write sftp-compatible (and thus new-duplicity-compatible)

sshoptions setting (Closes: #388543)

ChangeLog

@@ -60,7 +60,8 @@ version 0.9.4 -- unreleased
 	 . Does not pretend anymore that duplicity can work without
 	   any passphrase
 	 . Support duplicity 0.4.2 (with Debian patches applied; upstream's
-	   0.4.3 will integrate them)
+	   0.4.3 will integrate them); documented how to write sftp-compatible
+           sshoptions (Closes: #388543)
 	 . Now forbid to (try to) include /.
 	sys:
 	 . Many more system checks were added, (thanks to Petr Klíma)

NEWS

@@ -15,6 +15,14 @@ backupninja (0.9.4-1) UNRELEASED
 	  or /usr/share/doc/backupninja/examples/example.rdiff file, and update
 	  your own configuration files if needed.
 
+	* duplicity: duplicity now uses sftp, which does not support all scp
+	  command line options; you thus have to convert the sshoptions setting
+	  in your *.dup configuration files, to sftp-compatible syntax; for
+	  example, you can replace:
+	    sshoptions = -i /root/.ssh/id_dsa_duplicity
+	  with:
+	    sshoptions = -o IdentityFile=/root/.ssh/id_dsa_duplicity
+	
 backupninja (0.9.2-1) unstable; urgency=low
 
 WARNING FOR DUPLICITY USERS

examples/example.dup

@@ -119,8 +119,10 @@ exclude = /home/*/.gnupg
 # bandwith limit, in kbit/s ; default is 0, i.e. no limit
 #bandwidthlimit = 128
 
-# passed directly to ssh and scp
-sshoptions = -i /root/.ssh/id_dsa_duplicity
+# passed directly to ssh, scp (and sftp in duplicity >=0.4.2)
+# warning: sftp does not support all scp options, especially -i; as
+# a workaround, you can use "-o <SSHOPTION>"
+sshoptions = -o IdentityFile=/root/.ssh/id_dsa_duplicity
 
 # put the backups under this directory
 destdir = /backups

handlers/dup.helper

@@ -401,8 +401,10 @@ keep = $dup_keep
 #bandwidthlimit = 128
 bandwidthlimit = $dup_bandwidth
 
-# passed directly to ssh and scp
-#sshoptions = -i /root/.ssh/id_dsa_duplicity
+# passed directly to ssh, scp (and sftp in duplicity >=0.4.2)
+# warning: sftp does not support all scp options, especially -i; as
+# a workaround, you can use "-o <SSHOPTION>"
+#sshoptions = -o IdentityFile=/root/.ssh/id_dsa_duplicity
 sshoptions = $dup_sshoptions
 
 # put the backups under this directory