Add 'git svn reset' to unwind 'git svn fetch'

Add a command to unwind the effects of fetch by moving the rev_map
and refs/remotes/git-svn back to an old SVN revision.  This allows
revisions to be re-fetched.  Ideally SVN revs would be immutable,
but permissions changes in the SVN repository or indiscriminate use
of '--ignore-paths' can create situations where fetch cannot make
progress.

Signed-off-by: Ben Jackson <ben@ben.com>
Acked-by: Eric Wong <normalperson@yhbt.net>

t/t9139-git-svn-reset.sh

@@ -0,0 +1,66 @@
+#!/bin/sh
+#
+# Copyright (c) 2009 Ben Jackson
+#
+
+test_description='git svn reset'
+. ./lib-git-svn.sh
+
+test_expect_success 'setup test repository' '
+	svn_cmd co "$svnrepo" s &&
+	(
+		cd s &&
+		mkdir vis &&
+		echo always visible > vis/vis.txt &&
+		svn_cmd add vis &&
+		svn_cmd commit -m "create visible files" &&
+		mkdir hid &&
+		echo initially hidden > hid/hid.txt &&
+		svn_cmd add hid &&
+		svn_cmd commit -m "create initially hidden files" &&
+		svn_cmd up &&
+		echo mod >> vis/vis.txt &&
+		svn_cmd commit -m "modify vis" &&
+		svn_cmd up
+	)
+'
+
+test_expect_success 'clone SVN repository with hidden directory' '
+	git svn init "$svnrepo" g &&
+	( cd g && git svn fetch --ignore-paths="^hid" )
+'
+
+test_expect_success 'modify hidden file in SVN repo' '
+	( cd s &&
+	  echo mod hidden >> hid/hid.txt &&
+	  svn_cmd commit -m "modify hid" &&
+	  svn_cmd up
+	)
+'
+
+test_expect_success 'fetch fails on modified hidden file' '
+	( cd g &&
+	  git svn find-rev refs/remotes/git-svn > ../expect &&
+	  ! git svn fetch 2> ../errors &&
+	  git svn find-rev refs/remotes/git-svn > ../expect2 ) &&
+	fgrep "not found in commit" errors &&
+	test_cmp expect expect2
+'
+
+test_expect_success 'reset unwinds back to r1' '
+	( cd g &&
+	  git svn reset -r1 &&
+	  git svn find-rev refs/remotes/git-svn > ../expect2 ) &&
+	echo 1 >expect &&
+	test_cmp expect expect2
+'
+
+test_expect_success 'refetch succeeds not ignoring any files' '
+	( cd g &&
+	  git svn fetch &&
+	  git svn rebase &&
+	  fgrep "mod hidden" hid/hid.txt
+	)
+'
+
+test_done