test case for regression caused by git-svn empty symlink fix

Commit dbc6c74d "git-svn: handle empty
files marked as symlinks in SVN" caused a regression in an unusual case
where a branch has been created in SVN, later deleted and then created
again from another branch point and the original branch point had empty
files not in the new branch. In some cases git svn fetch will then fail
while trying to fetch the empty file from the wrong SVN revision.

This adds a test case that reproduces the issue.

[ew: added additional test to ensure file was created correctly
     made test file executable ]
Signed-off-by: NAnton Gyllenberg <anton@iki.fi>
Acked-by: NEric Wong <normalperson@yhbt.net>

t/t9135-git-svn-moved-branch-empty-file.sh

+#!/bin/sh
+
+test_description='test moved svn branch with missing empty files'
+
+. ./lib-git-svn.sh
+test_expect_success 'load svn dumpfile'  '
+	svnadmin load "$rawsvnrepo" < "${TEST_DIRECTORY}/t9135/svn.dump"
+	'
+
+test_expect_success 'clone using git svn' 'git svn clone -s "$svnrepo" x'
+
+test_expect_success 'test that b1 exists and is empty' '
+	(cd x && test -f b1 && ! test -s b1)
+	'
+
+test_done

t/t9135/svn.dump

+SVN-fs-dump-format-version: 2
+
+UUID: 1f80e919-e9e3-4d80-a3ae-d9f21095e27b
+
+Revision-number: 0
+Prop-content-length: 56
+Content-length: 56
+
+K 8
+svn:date
+V 27
+2009-02-10T19:23:16.424027Z
+PROPS-END
+
+Revision-number: 1
+Prop-content-length: 123
+Content-length: 123
+
+K 7
+svn:log
+V 20
+init standard layout
+K 10
+svn:author
+V 8
+john.doe
+K 8
+svn:date
+V 27
+2009-02-10T19:23:17.195072Z
+PROPS-END
+
+Node-path: branches
+Node-kind: dir
+Node-action: add
+Prop-content-length: 10
+Content-length: 10
+
+PROPS-END
+
+
+Node-path: trunk
+Node-kind: dir
+Node-action: add
+Prop-content-length: 10
+Content-length: 10
+
+PROPS-END
+
+
+Revision-number: 2
+Prop-content-length: 121
+Content-length: 121
+
+K 7
+svn:log
+V 18
+branch-b off trunk
+K 10
+svn:author
+V 8
+john.doe
+K 8
+svn:date
+V 27
+2009-02-10T19:23:19.160095Z
+PROPS-END
+
+Node-path: branches/branch-b
+Node-kind: dir
+Node-action: add
+Node-copyfrom-rev: 1
+Node-copyfrom-path: trunk
+Prop-content-length: 34
+Content-length: 34
+
+K 13
+svn:mergeinfo
+V 0
+
+PROPS-END
+
+
+Revision-number: 3
+Prop-content-length: 120
+Content-length: 120
+
+K 7
+svn:log
+V 17
+add empty file b1
+K 10
+svn:author
+V 8
+john.doe
+K 8
+svn:date
+V 27
+2009-02-10T19:23:20.194568Z
+PROPS-END
+
+Node-path: branches/branch-b/b1
+Node-kind: file
+Node-action: add
+Prop-content-length: 10
+Text-content-length: 0
+Text-content-md5: d41d8cd98f00b204e9800998ecf8427e
+Content-length: 10
+
+PROPS-END
+
+
+Revision-number: 4
+Prop-content-length: 110
+Content-length: 110
+
+K 7
+svn:log
+V 8
+branch-c
+K 10
+svn:author
+V 8
+john.doe
+K 8
+svn:date
+V 27
+2009-02-10T19:23:21.169100Z
+PROPS-END
+
+Node-path: branches/branch-c
+Node-kind: dir
+Node-action: add
+Node-copyfrom-rev: 3
+Node-copyfrom-path: trunk
+
+
+Revision-number: 5
+Prop-content-length: 126
+Content-length: 126
+
+K 7
+svn:log
+V 23
+oops, wrong branchpoint
+K 10
+svn:author
+V 8
+john.doe
+K 8
+svn:date
+V 27
+2009-02-10T19:23:21.253557Z
+PROPS-END
+
+Node-path: branches/branch-c
+Node-action: delete
+
+
+Revision-number: 6
+Prop-content-length: 127
+Content-length: 127
+
+K 7
+svn:log
+V 24
+branch-c off of branch-b
+K 10
+svn:author
+V 8
+john.doe
+K 8
+svn:date
+V 27
+2009-02-10T19:23:21.314659Z
+PROPS-END
+
+Node-path: branches/branch-c
+Node-kind: dir
+Node-action: add
+Node-copyfrom-rev: 5
+Node-copyfrom-path: branches/branch-b
+Prop-content-length: 34
+Content-length: 34
+
+K 13
+svn:mergeinfo
+V 0
+
+PROPS-END
+
+