git-svn: correctly track revisions made to deleted branches

git-svn has never been able to handle deleted branches very well
because svn_ra_get_log() is all-or-nothing, meaning that if the
max revision passed to it does not contain the path we're
tracking, we miss all the revisions in the repository.

Branches fetched using --follow-parent still do this
sub-optimally (will be fixed soon).  --follow-parent will soon
become the default, so we will assume that when using get_log();

We will also avoid tracking revprops for revisions with no
path-related changes since otherwise we just end up pulling
logs to paths we don't care about.

Also added a test for this to t9104-git-svn-follow-parent.sh and
correctly commit the log message in the preceeding test (which
conflicted with a filename).

Signed-off-by: Eric Wong <normalperson@yhbt.net>

t/t9104-git-svn-follow-parent.sh

@@ -85,7 +85,7 @@ test_expect_success 'follow higher-level parent' "
         cd blob &&
                 echo hi > hi &&
                 svn add hi &&
-                svn commit -m 'hi' &&
+                svn commit -m 'hihi' &&
                 cd ..
         svn mkdir -m 'new glob at top level' $svnrepo/glob &&
         svn mv -m 'move blob down a level' $svnrepo/blob $svnrepo/glob/blob &&
@@ -93,6 +93,15 @@ test_expect_success 'follow higher-level parent' "
         git-svn fetch -i blob --follow-parent
         "
 
+test_expect_success 'follow deleted directory' "
+	svn mv -m 'bye!' $svnrepo/glob/blob/hi $svnrepo/glob/blob/bye&&
+	svn rm -m 'remove glob' $svnrepo/glob &&
+	git-svn init -i glob $svnrepo/glob &&
+	git-svn fetch -i glob &&
+	test \"\`git cat-file blob refs/remotes/glob~1:blob/bye\`\" = hi &&
+	test -z \"\`git ls-tree -z refs/remotes/glob\`\"
+	"
+
 test_debug 'gitk --all &'
 
 test_done