tests/test-extdiff.out

prepush: rewrite most of the code from scratch

For servers with branchmap support, the algorithm now works as follows:

1. A list of branches in outgoing changesets is created.
2. Using the remote branchmap, a check for new branches is performed.
3. A map (from branch to head list) of locally known remote heads before
   the push is created, and one which, after step 4, will contain the locally
   known remote heads after the push.
4. The post-push head map is updated with the outgoing changesets, using the
   branch cache update mechanism.
5. A check for new heads is performed, by comparing the length of the head list
   before and after push, for each branch. If there are new heads, an error
   depending on whether or not there are incoming changes on the branch,
   is returned.
6. If the push is allowed, a warning is written if there are incoming changes
   on any branches involved in the push.

For old servers, an algorithm similar to step 4-6 above is used to check for
new topological heads only.

Two bugs are also fixed:
1. Sometimes you would be allowed to push new branch heads without --force.
   A test for this case was added.
2. You would get the "note: unsynced remote changes!" warning if there were any
   incoming changesets, even if they were on unrelated branches.

adding a
adding b
Only in a: a
Only in a: b
diffing a.000000000000 a
hg falabala [OPTION]... [FILE]...

use 'echo' to diff repository (or selected files)

    Show differences between revisions for the specified files, using the
    'echo' program.

    When two revision arguments are given, then changes are shown between
    those revisions. If only one revision is specified then that revision is
    compared to the working directory, and, when no revisions are specified,
    the working directory files are compared to its parent.

options:

 -o --option   pass option to comparison program
 -r --rev      revision
 -c --change   change made by revision
 -I --include  include names matching the given patterns
 -X --exclude  exclude names matching the given patterns

use "hg -v help falabala" to show global options
diffing a.8a5febb7f867/a a.34eed99112ab/a
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
created new head
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
diffing a.2a13a4d2da36/a [tmp]/test-extdiff/a/a
diffing a.8a5febb7f867/a a.34eed99112ab/a
diffing a.2a13a4d2da36/a a.46c0e4daeb72/a
diff-like tools yield a non-zero exit code

% test extdiff of multiple files in tmp dir:
% diff in working directory, before
diff --git a/a b/a
--- a/a
+++ b/a
@@ -1,1 +1,1 @@
-a
+changed
diff --git a/b b/b
old mode 100644
new mode 100755
--- a/b
+++ b/b
@@ -1,1 +1,1 @@
-b
+changed
% edit with extdiff -p
% diff in working directory, after
diff --git a/a b/a
--- a/a
+++ b/a
@@ -1,1 +1,2 @@
-a
+changed
+edited
diff --git a/b b/b
old mode 100644
new mode 100755
--- a/b
+++ b/b
@@ -1,1 +1,2 @@
-b
+changed
+edited

% test extdiff with --option
this a.8a5febb7f867/a a.34eed99112ab/a
diffing this a.8a5febb7f867/a a.34eed99112ab/a