--- bzr-1.12/bzrlib/_patiencediff_c.c.orig	2009-02-13 15:36:09.000000000 +0000
+++ bzr-1.12/bzrlib/_patiencediff_c.c	2009-02-18 08:59:32.000000000 +0000
@@ -461,7 +461,7 @@
     last_b_pos = blo - 1;
 
     lcs = (struct matching_line *)malloc(sizeof(struct matching_line) * (bhi - blo));
-    if (lcs == NULL)
+    if (lcs == NULL && (bhi - blo) != 0)
         return 0;
 
     lcs_size = unique_lcs(lcs, hashtable, backpointers, a, b, alo, blo, ahi, bhi);
@@ -621,11 +621,11 @@
         goto error;
 
     matches = (struct matching_line *)malloc(sizeof(struct matching_line) * bsize);
-    if (matches == NULL)
+    if (matches == NULL && bsize != 0)
         goto error;
 
     backpointers = (Py_ssize_t *)malloc(sizeof(Py_ssize_t) * bsize * 4);
-    if (backpointers == NULL)
+    if (backpointers == NULL && bsize != 0)
         goto error;
 
     nmatches = unique_lcs(matches, &hashtable, backpointers, a, b, 0, 0, asize, bsize);
@@ -693,11 +693,11 @@
 
     matches.count = 0;
     matches.matches = (struct matching_block *)malloc(sizeof(struct matching_block) * bsize);
-    if (matches.matches == NULL)
+    if (matches.matches == NULL && bsize != 0)
         goto error;
 
     backpointers = (Py_ssize_t *)malloc(sizeof(Py_ssize_t) * bsize * 4);
-    if (backpointers == NULL)
+    if (backpointers == NULL && bsize != 0)
         goto error;
 
     res = recurse_matches(&matches, &hashtable, backpointers,
@@ -766,7 +766,7 @@
         }
 
         self->backpointers = (Py_ssize_t *)malloc(sizeof(Py_ssize_t) * self->bsize * 4);
-        if (self->backpointers == NULL) {
+        if (self->backpointers == NULL && self->bsize != 0) {
             Py_DECREF(self);
             PyErr_NoMemory();
             return NULL;
@@ -813,7 +813,7 @@
 
     matches.count = 0;
     matches.matches = (struct matching_block *)malloc(sizeof(struct matching_block) * self->bsize);
-    if (matches.matches == NULL)
+    if (matches.matches == NULL && self->bsize != 0)
         return PyErr_NoMemory();
 
     res = recurse_matches(&matches, &self->hashtable, self->backpointers,