gnu: tomb: Update to 2.7.

* gnu/packages/patches/tomb-fix-errors-on-open.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.
* gnu/packages/crypto.scm (tomb): Update to 2.7.
[source]: Use the patch.

gnu/packages/patches/tomb-fix-errors-on-open.patch

@@ -0,0 +1,25 @@
+Description: Avoid error messages when opening a new tomb
+ Make sure control file exists and has user ownership before user writes to it.
+Author: Sven Geuer <debmaint@g-e-u-e-r.de>
+Bug: https://github.com/dyne/Tomb/issues/369
+Last-Update: 2019-11-04
+--- a/tomb
++++ b/tomb
+@@ -2197,14 +2197,15 @@
+ # {{{ Open
+ 
+ _update_control_file() {
+-	# replaces a control file with new contents and gives it user ownership
++	# make sure a control file exists, gives it user ownership
++	# and replaces it with new contents
+ 	# stdin = contents
+ 	# $1 = path to control file
+ 	# $2 = contents
+ 	[[ "$2" = "" ]] && return 1
+ 	_sudo touch "$1"
+-	print "$2" > "$1"
+ 	_sudo chown ${_UID}:${_GID} "$1"
++	print "$2" > "$1"
+ 	_verbose "updated control file $1 = $2"
+ }
+