Fix select_to_reverse to correctly handle the first character of the buffer

Fixes #809

src/selectors.cc

@@ -229,8 +229,8 @@ Selection select_to_reverse(const Buffer& buffer, const Selection& selection,
     do
     {
         --end;
-        skip_while_reverse(end, buffer.begin(), [c](Codepoint cur) { return cur != c; });
-        if (end == buffer.begin())
+        if (skip_while_reverse(end, buffer.begin(),
+                               [c](Codepoint cur) { return cur != c; }))
             return selection;
     }
     while (--count > 0);

test/regression/809-alt-f-t-to-first-char/cmd

@@ -0,0 +1 @@
+<a-f>f

test/regression/809-alt-f-t-to-first-char/in

@@ -0,0 +1 @@
+fooba%(r)

test/regression/809-alt-f-t-to-first-char/selections

@@ -0,0 +1 @@
+foobar