diff --git a/Documentation/RelNotes-1.5.4.7.txt b/Documentation/RelNotes-1.5.4.7.txt
new file mode 100644
index 0000000000..9065a0e273
--- /dev/null
+++ b/Documentation/RelNotes-1.5.4.7.txt
@@ -0,0 +1,10 @@
+GIT v1.5.4.7 Release Notes
+==========================
+
+Fixes since 1.5.4.7
+-------------------
+
+ * Removed support for an obsolete gitweb request URI, whose
+   implementation ran "git diff" Porcelain, instead of using plumbing,
+   which would have run an external diff command specified in the
+   repository configuration as the gitweb user.
diff --git a/Documentation/RelNotes-1.5.5.6.txt b/Documentation/RelNotes-1.5.5.6.txt
new file mode 100644
index 0000000000..d5e85cb70e
--- /dev/null
+++ b/Documentation/RelNotes-1.5.5.6.txt
@@ -0,0 +1,10 @@
+GIT v1.5.5.6 Release Notes
+==========================
+
+Fixes since 1.5.5.5
+-------------------
+
+ * Removed support for an obsolete gitweb request URI, whose
+   implementation ran "git diff" Porcelain, instead of using plumbing,
+   which would have run an external diff command specified in the
+   repository configuration as the gitweb user.
diff --git a/Documentation/RelNotes-1.5.6.6.txt b/Documentation/RelNotes-1.5.6.6.txt
new file mode 100644
index 0000000000..79da23db5a
--- /dev/null
+++ b/Documentation/RelNotes-1.5.6.6.txt
@@ -0,0 +1,10 @@
+GIT v1.5.6.6 Release Notes
+==========================
+
+Fixes since 1.5.6.5
+-------------------
+
+ * Removed support for an obsolete gitweb request URI, whose
+   implementation ran "git diff" Porcelain, instead of using plumbing,
+   which would have run an external diff command specified in the
+   repository configuration as the gitweb user.
diff --git a/RelNotes b/RelNotes
index 1c0163594a..6ca1d5b439 120000
--- a/RelNotes
+++ b/RelNotes
@@ -1 +1 @@
-Documentation/RelNotes-1.5.6.5.txt
\ No newline at end of file
+Documentation/RelNotes-1.5.6.6.txt
\ No newline at end of file
diff --git a/gitweb/gitweb.perl b/gitweb/gitweb.perl
index 49b01d8c25..f88ce35ce8 100755
--- a/gitweb/gitweb.perl
+++ b/gitweb/gitweb.perl
@@ -4926,43 +4926,9 @@ sub git_blobdiff {
 			or die_error(undef, "Open git-diff-tree failed");
 	}
 
-	# old/legacy style URI
-	if (!%diffinfo && # if new style URI failed
-	    defined $hash && defined $hash_parent) {
-		# fake git-diff-tree raw output
-		$diffinfo{'from_mode'} = $diffinfo{'to_mode'} = "blob";
-		$diffinfo{'from_id'} = $hash_parent;
-		$diffinfo{'to_id'}   = $hash;
-		if (defined $file_name) {
-			if (defined $file_parent) {
-				$diffinfo{'status'} = '2';
-				$diffinfo{'from_file'} = $file_parent;
-				$diffinfo{'to_file'}   = $file_name;
-			} else { # assume not renamed
-				$diffinfo{'status'} = '1';
-				$diffinfo{'from_file'} = $file_name;
-				$diffinfo{'to_file'}   = $file_name;
-			}
-		} else { # no filename given
-			$diffinfo{'status'} = '2';
-			$diffinfo{'from_file'} = $hash_parent;
-			$diffinfo{'to_file'}   = $hash;
-		}
-
-		# non-textual hash id's can be cached
-		if ($hash =~ m/^[0-9a-fA-F]{40}$/ &&
-		    $hash_parent =~ m/^[0-9a-fA-F]{40}$/) {
-			$expires = '+1d';
-		}
-
-		# open patch output
-		open $fd, "-|", git_cmd(), "diff", @diff_opts,
-			'-p', ($format eq 'html' ? "--full-index" : ()),
-			$hash_parent, $hash, "--"
-			or die_error(undef, "Open git-diff failed");
-	} else  {
+	# old/legacy style URI -- not generated anymore since 1.4.3.
+	if (!%diffinfo) {
 		die_error('404 Not Found', "Missing one of the blob diff parameters")
-			unless %diffinfo;
 	}
 
 	# header