py3: replace file() with open() in test-patch-offset.t

file() is not present in Python 3.

Differential Revision: https://phab.mercurial-scm.org/D2119

tests/test-patch-offset.t

@@ -1,82 +1,82 b''
 
   $ cat > writepatterns.py <<EOF
   > import sys
   > 
   > path = sys.argv[1]
   > patterns = sys.argv[2:]
   > 
-  > fp = file(path, 'wb')
+  > fp = open(path, 'wb')
   > for pattern in patterns:
   >     count = int(pattern[0:-1])
   >     char = pattern[-1] + '\n'
   >     fp.write(char*count)
   > fp.close()
   > EOF
 
 prepare repo
 
   $ hg init a
   $ cd a
 
 These initial lines of Xs were not in the original file used to generate
 the patch.  So all the patch hunks need to be applied to a constant offset
 within this file.  If the offset isn't tracked then the hunks can be
 applied to the wrong lines of this file.
 
   $ $PYTHON ../writepatterns.py a 34X 10A 1B 10A 1C 10A 1B 10A 1D 10A 1B 10A 1E 10A 1B 10A
   $ hg commit -Am adda
   adding a
 
 This is a cleaner patch generated via diff
 In this case it reproduces the problem when
 the output of hg export does not
 import patch
 
   $ hg import -v -m 'b' -d '2 0' - <<EOF
   > --- a/a	2009-12-08 19:26:17.000000000 -0800
   > +++ b/a	2009-12-08 19:26:17.000000000 -0800
   > @@ -9,7 +9,7 @@
   >  A
   >  A
   >  B
   > -A
   > +a
   >  A
   >  A
   >  A
   > @@ -53,7 +53,7 @@
   >  A
   >  A
   >  B
   > -A
   > +a
   >  A
   >  A
   >  A
   > @@ -75,7 +75,7 @@
   >  A
   >  A
   >  B
   > -A
   > +a
   >  A
   >  A
   >  A
   > EOF
   applying patch from stdin
   patching file a
   Hunk #1 succeeded at 43 (offset 34 lines).
   Hunk #2 succeeded at 87 (offset 34 lines).
   Hunk #3 succeeded at 109 (offset 34 lines).
   committing files:
   a
   committing manifest
   committing changelog
   created 189885cecb41
 
 compare imported changes against reference file
 
   $ $PYTHON ../writepatterns.py aref 34X 10A 1B 1a 9A 1C 10A 1B 10A 1D 10A 1B 1a 9A 1E 10A 1B 1a 9A
   $ diff aref a
 
   $ cd ..