[libpeas] Fix building a clean checkout

[Garrett Regier <gregier src gnome org>]

commit 2b0339e493fd8dd1896bd942e075d0addfc63a49
Author: Garrett Regier <alias301 gmail com>
Date:   Thu Feb 17 22:13:36 2011 -0800

    Fix building a clean checkout

 tests/Makefile.plugin |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)
---
diff --git a/tests/Makefile.plugin b/tests/Makefile.plugin
index 640c4ef..aed0484 100644
--- a/tests/Makefile.plugin
+++ b/tests/Makefile.plugin
@@ -5,7 +5,9 @@
 all-local:
 	@test -z "$(noinst_PLUGIN)" || \
 	 for plugin in $(noinst_PLUGIN) ; do \
-	   if ! test -e $(builddir)/$$plugin ; then \
-	     cp -p $(srcdir)/$$plugin $(builddir)/ ; \
+	   if test -e $(srcdir)/$$plugin ; then \
+	     if ! test -e $(builddir)/$$plugin ; then \
+	       cp -p $(srcdir)/$$plugin $(builddir)/ ; \
+	     fi ; \
 	   fi ; \
 	 done