SVN via HTTPS Eclipse checkout failure

Hello,

I observe some weird behaviour with SVN checkouts via HTTPS using
Eclipse. Please advise on how to debug this further, or what component
to look at closer (details below):

 - Is this a server-side configuration issue?
 - Is it an Eclipse/Subversive issue which I should post on a related
    mailing list?
 - Both of the above?
 - Something I didn't think of at all?
 - Not decidable yet, further information (which?) needed?

Kind regards,
 Horst

The details:

* server-side: Apache2 with mod_dav_svn 1.4.3 (from Blastwave/CSW,
  running on Solaris 9)

* checkout, commit, etc. works _fine_ with the svn 1.4.2 command line
  client on Linux x86 (kdesvn works fine, too)
  (Apache's access log says (among lots of PROPFIND log entries):
   "REPORT /repos/xxx/!svn/vcc/default HTTP/1.1" 200 279670)

* repository _browsing_ works fine in Eclipse 3.2 (using SVN Team
  Provider 1.1.2 + SVNKit 1.1.1 or JavaSVN 1.0.4)

* repository _checkout_ fails in Eclipse with this error message (from
  "Details"):
  "Unusable URI: it does not refer to this repository
  REPORT of '/repos/xxx/!svn/vcc/default': 500 Internal Server Error (https://xxx.xxx.xxx)"

* Eclipse's Console View says
  "*** Check Out
  svn checkout "https://xxx.xxx.xxx/repos/xxx/trunk@HEAD" -r HEAD "/home/some_valid_target_dir" --username "myusername"
  svn: Unusable URI: it does not refer to this repository
  svn: REPORT of '/repos/xxx/!svn/vcc/default': 500 Internal Server Error (https://xxx.xxx.xxx/)
  *** Error (took 00:01.788)"

* Using exactly this "svn checkout ..." command line from a shell
  _works_ fine

* Apache's error log says
"Could not parse 'src-path' URL. [500, #190001]
Unusable URI: it does not refer to this repository [500, #190001]"

* Apache's access log says
"REPORT /repos/xxx/!svn/vcc/default HTTP/1.1" 500 246

* Checkouts from within Eclipse with repositories from another
  VirtualHost on that server _work_ (that's what makes me believe my
  Apache configuration is broken)

excerpt from httpd.conf:
--------------------------------------------------------
# virtual host for https://xxx.xxx.xxx/
<VirtualHost 131.188.xxx.xxx:443>

# General setup for the virtual host
  DocumentRoot "/opt/csw/apache2/share/htdocs"
  ServerName xxx.xxx.xxx:443
  ServerAdmin webmaster@xxx.xxx.xxx
  ErrorLog /opt/csw/apache2/var/log/xxx_error_log
  TransferLog /opt/csw/apache2/var/log/xxx_access_log

  Include etc/ssl-xxx.conf

  <Location /repos>
    DAV svn
    SVNParentPath /proj/xxx
    AuthzSVNAccessFile /proj/xxx/svn-access-file
    AuthType Basic
    AuthName "xxx"
    AuthUserFile /proj/xxx/svn-auth-file
    Require valid-user
  </Location>
</VirtualHost>

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