git-svn: fix dcommit losing changes when out-of-date from svn

There was a bug in dcommit (and commit-diff) which caused deltas
to be generated against the latest version of the changed file
in a repository, and not the revision we are diffing (the tree)
against locally.

This bug can cause recent changes to the svn repository to be
silently clobbered by git-svn if our repository is out-of-date.

Thanks to Steven Grimm for noticing the bug.

The (few) people using the commit-diff command are now required
to use the -r/--revision argument.  dcommit usage is unchanged.

Signed-off-by: Eric Wong <normalperson@yhbt.net>
Signed-off-by: Junio C Hamano <junkio@cox.net>

t/t9106-git-svn-commit-diff-clobber.sh

@@ -0,0 +1,74 @@
+#!/bin/sh
+#
+# Copyright (c) 2006 Eric Wong
+test_description='git-svn commit-diff clobber'
+. ./lib-git-svn.sh
+
+if test -n "$GIT_SVN_NO_LIB" && test "$GIT_SVN_NO_LIB" -ne 0
+then
+	echo 'Skipping: commit-diff clobber needs SVN libraries'
+	test_done
+	exit 0
+fi
+
+test_expect_success 'initialize repo' "
+	mkdir import &&
+	cd import &&
+	echo initial > file &&
+	svn import -m 'initial' . $svnrepo &&
+	cd .. &&
+	echo initial > file &&
+	git update-index --add file &&
+	git commit -a -m 'initial'
+	"
+test_expect_success 'commit change from svn side' "
+	svn co $svnrepo t.svn &&
+	cd t.svn &&
+	echo second line from svn >> file &&
+	svn commit -m 'second line from svn' &&
+	cd .. &&
+	rm -rf t.svn
+	"
+
+test_expect_failure 'commit conflicting change from git' "
+	echo second line from git >> file &&
+	git commit -a -m 'second line from git' &&
+	git-svn commit-diff -r1 HEAD~1 HEAD $svnrepo
+	" || true
+
+test_expect_success 'commit complementing change from git' "
+	git reset --hard HEAD~1 &&
+	echo second line from svn >> file &&
+	git commit -a -m 'second line from svn' &&
+	echo third line from git >> file &&
+	git commit -a -m 'third line from git' &&
+	git-svn commit-diff -r2 HEAD~1 HEAD $svnrepo
+	"
+
+test_expect_failure 'dcommit fails to commit because of conflict' "
+	git-svn init $svnrepo &&
+	git-svn fetch &&
+	git reset --hard refs/remotes/git-svn &&
+	svn co $svnrepo t.svn &&
+	cd t.svn &&
+	echo fourth line from svn >> file &&
+	svn commit -m 'fourth line from svn' &&
+	cd .. &&
+	rm -rf t.svn &&
+	echo 'fourth line from git' >> file &&
+	git commit -a -m 'fourth line from git' &&
+	git-svn dcommit
+	" || true
+
+test_expect_success 'dcommit does the svn equivalent of an index merge' "
+	git reset --hard refs/remotes/git-svn &&
+	echo 'index merge' > file2 &&
+	git update-index --add file2 &&
+	git commit -a -m 'index merge' &&
+	echo 'more changes' >> file2 &&
+	git update-index file2 &&
+	git commit -a -m 'more changes' &&
+	git-svn dcommit
+	"
+
+test_done