[PATCH RFC] import: tweak diff line detection in patch header regex (issue1879)

[Levi Bard]

# HG changeset patch
# User Levi Bard <levi at unity3d.com>
# Date 1336921918 -7200
# Node ID 03e0651bf4c3d7a8515d79cc222be905b8073bbd
# Parent  0a176990243c9b4753039867164cfed560806fb7
import: tweak diff line detection in patch header regex (issue1879)

diff -r 0a176990243c -r 03e0651bf4c3 mercurial/patch.py
--- a/mercurial/patch.py	Sun May 13 14:29:05 2012 +0200
+++ b/mercurial/patch.py	Sun May 13 17:11:58 2012 +0200
@@ -160,10 +160,12 @@
 
     # attempt to detect the start of a patch
     # (this heuristic is borrowed from quilt)
-    diffre = re.compile(r'^(?:Index:[ \t]|diff[ \t]|RCS file: |'
-                        r'retrieving revision [0-9]+(\.[0-9]+)*$|'
-                        r'---[ \t].*?^\+\+\+[ \t]|'
-                        r'\*\*\*[ \t].*?^---[ \t])', re.MULTILINE|re.DOTALL)
+    diffre = re.compile(r'^(?:Index:[ \t]|'
+    r'diff[ \t]+(--?[\w][-\w]*[ \t]+(\S+)?[ \t]*)*' # diff -x y --z-1 2
+    r'(\S+[ \t]*){0,2}[ \t\r]*$' # zero to two non-option args (a/a b/a)
+    r'|RCS file: |retrieving revision \d+(\.\d+)*$|'
+    r'---[ \t].*?^\+\+\+[ \t]|\*\*\*[ \t].*?^---[ \t])',
+    re.MULTILINE|re.DOTALL)
 
     fd, tmpname = tempfile.mkstemp(prefix='hg-patch-')
     tmpfp = os.fdopen(fd, 'w')
diff -r 0a176990243c -r 03e0651bf4c3 tests/test-import.t
--- a/tests/test-import.t	Sun May 13 14:29:05 2012 +0200
+++ b/tests/test-import.t	Sun May 13 17:11:58 2012 +0200
@@ -167,6 +167,36 @@
   [255]
   $ rm -r b
 
+  $ cat > spurious-diff-line.diff <<EOF
+  > summary line
+  > 
+  > this is a message containing the word
+  > diff in a strategic place
+  > 
+  > diff --git a/test.txt b/test.txt
+  > new file mode 100644
+  > 
+  > EOF
+  $ hg clone -r0 a b
+  adding changesets
+  adding manifests
+  adding file changes
+  added 1 changesets with 2 changes to 2 files
+  updating to branch default
+  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ hg --cwd b import ../spurious-diff-line.diff
+  applying ../spurious-diff-line.diff
+  $ hg --cwd b log --template '===\n{desc}\n===\n'
+  ===
+  summary line
+  
+  this is a message containing the word
+  diff in a strategic place
+  ===
+  ===
+  a
+  ===
+  $ rm -r b
 
 hg -R repo import
 put the clone in a subdir - having a directory named "a"