[SVN-4610] svn patch - improve detection of reversed or already-applied patches

• Type: Bug
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Affects Version/s: 1.8.15, 1.9.3
• Component/s: libsvn_client
• Assignee: Unassigned
• Reporter: Julian Foad
• Created: 23/Dec/15 10:56
• Updated: 23/Dec/15 10:56

Description

svn patch sometimes fails to detect when a patch has already been applied, whereas GNU patch does detect that and warn.

This example involves a patch that is applied with fuzz and offset. This was observed and reported by one of WANdisco's customers, with a real patch to some *BSD source code; I have reduced one of their test cases to a small abstract example here.

Example:

file1

A
B
C
D

E

F

G

patch1

Index: file1
===================================================================
--- file1       (revision 1)
+++ file1       (working copy)
@@ -7,6 +7,8 @@
 C
 D

+E
+
 F

 G

test.log

$ svn --version -q
1.9.3
$ svn patch patch1
U         file1
>         applied hunk @@ -7,6 +7,8 @@ with offset -2 and fuzz 2
$ svn revert -q file1
$ patch --version | head -1
GNU patch 2.7.1
$ patch < patch1
patching file file1
Reversed (or previously applied) patch detected!  Assume -R? [n]