Do not take the repository db.lock for FSFS repositories.
This might let FSFS repositories work on Win9x.

* subversion/include/svn_fs.h (svn_fs_type): New API. Get the type of a FS.
* subversion/libsvn_fs/fs-loader.c (svn_fs_type): New API, functionality
    extracted from fs_library_vtable().
  (fs_library_vtable): Use svn_fs_type().
* subversion/libsvn_repos/repos.c (get_repos):
    Skip locking for FSFS repositories.
  
Index: subversion/include/svn_fs.h
===================================================================
--- subversion/include/svn_fs.h	(revision 15801)
+++ subversion/include/svn_fs.h	(working copy)
@@ -169,6 +169,15 @@
                           apr_hash_t *config, apr_pool_t *pool);
 
 /**
+ * Discover the type of a Subversion filesystem located in the directory
+ * @a path.
+ * 
+ * @since New in 1.3.
+ */
+svn_error_t *svn_fs_type (const char **fs_type, const char *path,
+                          apr_pool_t *pool);
+
+/**
  * Return the path to @a fs's repository, allocated in @a pool.
  * @note This is just what was passed to svn_fs_create() or
  * svn_fs_open() -- might be absolute, might not.
Index: subversion/libsvn_fs/fs-loader.c
===================================================================
--- subversion/libsvn_fs/fs-loader.c	(revision 15801)
+++ subversion/libsvn_fs/fs-loader.c	(working copy)
@@ -163,12 +163,10 @@
                             _("Unknown FS type '%s'"), fs_type);
 }
 
-/* Fetch the library vtable for an existing FS. */
-static svn_error_t *
-fs_library_vtable (fs_library_vtable_t **vtable, const char *path,
-                   apr_pool_t *pool)
+svn_error_t *
+svn_fs_type (const char **fs_type, const char *path, apr_pool_t *pool)
 {
-  const char *filename, *fs_type;
+  const char *filename, *local_fs_type;
   char buf[128];
   svn_error_t *err;
   apr_file_t *file;
@@ -180,7 +178,7 @@
   if (err && APR_STATUS_IS_ENOENT (err->apr_err))
     {
       svn_error_clear (err);
-      fs_type = SVN_FS_TYPE_BDB;
+      local_fs_type = SVN_FS_TYPE_BDB;
     }
   else if (err)
     return err;
@@ -189,10 +187,24 @@
       len = sizeof(buf);
       SVN_ERR (svn_io_read_length_line (file, buf, &len, pool));
       SVN_ERR (svn_io_file_close (file, pool));
-      fs_type = buf;
+      local_fs_type = buf;
     }
 
   /* Fetch the library vtable by name, now that we've chosen one. */
+  *fs_type = apr_pstrdup (pool, local_fs_type);
+  return SVN_NO_ERROR;
+}
+
+/* Fetch the library vtable for an existing FS. */
+static svn_error_t *
+fs_library_vtable (fs_library_vtable_t **vtable, const char *path,
+                   apr_pool_t *pool)
+{
+  const char *fs_type;
+
+  SVN_ERR (svn_fs_type (&fs_type, path, pool));
+
+  /* Fetch the library vtable by name, now that we've chosen one. */
   return get_library_vtable (vtable, fs_type, pool);
 }
 
Index: subversion/libsvn_repos/repos.c
===================================================================
--- subversion/libsvn_repos/repos.c	(revision 15801)
+++ subversion/libsvn_repos/repos.c	(working copy)
@@ -1646,16 +1646,30 @@
 
   /* Locking. */
   {
-    const char *lockfile_path;
-    svn_error_t *err;
+    const char *fs_type;
 
-    /* Get a filehandle for the repository's db lockfile. */
-    lockfile_path = svn_repos_db_lockfile (repos, pool);
+    SVN_ERR (svn_fs_type (&fs_type, repos->db_path, pool));
 
-    err = svn_io_file_lock2 (lockfile_path, exclusive, nonblocking, pool);
-    if (err != NULL && APR_STATUS_IS_EAGAIN (err->apr_err))
-      return err;
-    SVN_ERR_W (err, _("Error opening db lockfile"));
+    if (!strcmp (fs_type, SVN_FS_TYPE_FSFS))
+      {
+        /* Skip locking for FSFS repositories, because it is not necessary,
+         * and because Win9x is lame, and doesn't support shared locks,
+         * locking anyway actually kills our ability to host repositories
+         * on Win9x. */
+      }
+    else
+      {
+        const char *lockfile_path;
+        svn_error_t *err;
+
+        /* Get a filehandle for the repository's db lockfile. */
+        lockfile_path = svn_repos_db_lockfile (repos, pool);
+
+        err = svn_io_file_lock2 (lockfile_path, exclusive, nonblocking, pool);
+        if (err != NULL && APR_STATUS_IS_EAGAIN (err->apr_err))
+          return err;
+        SVN_ERR_W (err, _("Error opening db lockfile"));
+      }
   }
 
   /* Open up the filesystem only after obtaining the lock. */