Allow merging with empty pdiff patches

There isn't a lot of sense in working on empty patches as they change
nothing (quite literally), but they can be the result of merging
multiple patches and so to not require our users to specifically detect
and remove them, we can be nice and just ignore them instead of erroring
out.

1 files changed, 5 insertions, 1 deletions

diff --git a/methods/rred.cc b/methods/rred.cc
index f53f05ad5..3453bd3bc 100644
--- a/methods/rred.cc
+++ b/methods/rred.cc
@@ -441,8 +441,12 @@ class Patch {
       bool cmdwanted = true;
 
       Change ch(std::numeric_limits<size_t>::max());
-      if (f.ReadLine(buffer, sizeof(buffer)) == NULL)
+      if (f.ReadLine(buffer, sizeof(buffer)) == nullptr)
+      {
+	 if (f.Eof())
+	    return true;
 	 return _error->Error("Reading first line of patchfile %s failed", f.Name().c_str());
+      }
       do {
 	 if (h != NULL)
 	    h->Add(buffer);