Fix inconsistent backslash escaping

advtrains/poconvert.lua

@@ -13,12 +13,12 @@ do
 	local function replace_single(pfx, c)
 		local pl = #pfx
 		if pl % 2 == 0 then
-			return pfx .. c
+			return pfx:sub(1, pl/2) .. c
 		end
 		return string.sub(pfx, 1, math.floor(pl/2)) .. (schartbl[c] or c)
 	end
 	unescape_string = function(str)
-		return (string.gsub(str, [[(\+)([abefnrtv'"?])]], replace_single):gsub([[\\]], [[\]]))
+		return string.gsub(str, [[(\+)([abefnrtv'"?])]], replace_single)
 	end
 end
 

advtrains/spec/poconvert_spec.lua

@@ -9,7 +9,7 @@ describe("PO file converter", function()
 # textdomain: foo
 foo=bar
 baz=
-#@=wh\at\@n=@=w\as\@n
+#@=wh\at\\@n=@=w\as\\@n
 multiline@nstrings=
 with context?=oder doch nicht]], poconvert.from_string("foo", [[
 msgid ""
@@ -22,8 +22,8 @@ msgid "baz"
 msgstr ""
 
 #, fuzzy
-msgid "=wh\\at\\\n"
-msgstr "=w\\as\\\n"
+msgid "=wh\\at\\\\\n"
+msgstr "=w\\as\\\\\n"
 
 msgid "multi"
 "line\n"