cygwin中svn版本过低无法读取高版本的workcopy的问题
由于工作环境依赖于cygwin，TortoiseSVN .
之前的TortoiseSVN 比较消耗系统资源，经常弄得系统无响应。升级到TortoiseSVN 1.6.2版本后，这个问题得到了较好的解决，可随之而来的问题是：cygwin中svn的版本是1.4.5, 无法读取TortoiseSVN 1.6.2的workcopy。而本人偶尔会使用命令行来处理一些事情，在经过一番google后，终于搞定了。
在TortoiseSVN 1.6.2的work copy目录下使用 svn info 得到如下的提示：
$ svn info
svn: This client is too old to work with working copy '.'; please get a newer Su
bversion client
看来是cygwin中的svn版本很低
$ svn --version
svn, version 1.4.5 (r25188)
compiled Sep 19 2007, 23:10:31
Copyright (C) 2000-2006 CollabNet.
Subversion is open source software, see http://subversion.tigris.org/
This product includes software developed by CollabNet (http://www.Collab.Net/).
The following repository access (RA) modules are available:
* ra_dav : Module for accessing a repository via WebDAV (DeltaV) protocol.
- handles 'http' scheme
- handles 'https' scheme
* ra_svn : Module for accessing a repository using the svn network protocol.
- handles 'svn' scheme
* ra_local : Module for accessing a repository on local disk.
- handles 'file' scheme
确实有点低，google一下没有找到cygwin先有新的版本，于是下载subversion-1.6.2.tar.gz，按照READE和INSTALL的说明 一步一步从源代码编译安装。
刚开始一切都很顺利，可到了 make时却出现了错误：
.libs/fs_fs.o: In function `svn_fs_fs__add_change':
/cygdrive/d/subversion-1.6.2/subversion/libsvn_fs_fs/fs_fs.c:4783: undefined ref
erence to `_svn_fs_path_change2_create'
Creating library file: .libs/libsvn_fs_fs-1.dll.a
collect2: ld returned 1 exit status
make: *** [subversion/libsvn_fs_fs/libsvn_fs_fs-1.la] Error 1
有Google了一番，重新仔细阅读README INSTALL ,rm libsvn*等等，还是没有解决。
快要崩溃时，想到了 Subversion FAQ，还真找到了，FAQ啊 太帅了：
I get an error that says "This client is too old".
You're using both an older (pre-1.4) version of the Subversion command-line client, and Subclipse. You recently upgraded Subclipse, and now your command-line client sayssvn: This client is too old to work with working copyThis happened because Subversion's working-copy format changed incompatibly—the new version of Subclipse upgraded your working copy, so now your command-line program, which is old, cannot read it. (This problem isn't specific to Subclipse; it would also have happened if you'd used a command-line client that was 1.4 or newer, along with your older command-line client.) The fix is simply to upgrade your command-line client to 1.4 or newer. As of Subversion 1.5, a helper script is provided to downgrade working copies to formats compatible with earlier releases of Subversion; see this faq.
'/path/to/your/working/copy'; please get a newer Subversion client
I got an error saying "This client is too old to work with working copy '...' ". How can I fix it without upgrading Subversion?
Sometimes the working copy metadata format changes incompatibly between minor releases. For example, say you have a working copy created with Subversion 1.4.4, but one day you decide to try out Subversion 1.5.0. Afterwards, you attempt to switch back to 1.4.4, but it doesn't work — it just gives the above error.
This is because 1.5.0 upgraded your working copy format to support some new features (in this case, changelists, the keep-local flag, and variable-depth directories). Although 1.4.4 doesn't know anything about these new features, it can at least recognize that the working copy format has been upgraded to something higher than it can handle.
1.5.0 upgraded the working copy for a good reason: it realizes that 1.4.4 does not know about these new features, and that if 1.4.4 were to meddle with the working copy metadata now, important information might be lost, possibly causing corruption (see issue #2961 , for example).
But this automatic upgrade behavior can be annoying, if you just want to try out a new release of Subversion without installing it permanently. For this reason, we distribute a script that can downgrade working copies when doing so is safe:
http://svn.collab.net/repos/svn/trunk/tools/client-side/change-svn-wc-format.py
Run that script with the "--help " option to see how to use it. As future versions of Subversion are released, we will try to keep this FAQ entry up-to-date with potential downgrade scenarios and their implications.