new upgade042 pactest + bugfix in chk_filedifference.

This adds a pactest for the relocation of a config file between two packages
(case of etc/profile moving from bash to filesystem).
While running this pactest, I found out that chk_filedifference didn't work
correctly with an empty list as second argument. So that's fixed now.

Ref: http://www.archlinux.org/pipermail/pacman-dev/2007-December/010610.html

Signed-off-by: Chantry Xavier <shiningxc@gmail.com>
Signed-off-by: Dan McGee <dan@archlinux.org>

lib/libalpm/conflict.c

@@ -251,6 +251,10 @@ static alpm_list_t *chk_filedifference(alpm_list_t *filesA, alpm_list_t *filesB)
 	alpm_list_t *ret = NULL;
 	alpm_list_t *pA = filesA, *pB = filesB;
 
+	if(pB == NULL) {
+		return(alpm_list_strdup(pA));
+	}
+
 	while(pA && pB) {
 		const char *strA = pA->data;
 		const char *strB = pB->data;

pactest/tests/upgrade042.py

@@ -0,0 +1,28 @@
+self.description = "Backup file relocation"
+
+lp1 = pmpkg("bash")
+lp1.files = ["etc/profile*"]
+lp1.backup = ["etc/profile"]
+self.addpkg2db("local", lp1)
+
+p1 = pmpkg("bash", "1.0-2")
+self.addpkg(p1)
+
+lp2 = pmpkg("filesystem")
+self.addpkg2db("local", lp2)
+
+p2 = pmpkg("filesystem", "1.0-2")
+p2.files = ["etc/profile**"]
+p2.backup = ["etc/profile"]
+p2.depends = [ "bash" ]
+self.addpkg(p2)
+
+self.args = "-U %s" % " ".join([p.filename() for p in p1, p2])
+
+self.filesystem = ["etc/profile"]
+
+self.addrule("PKG_VERSION=bash|1.0-2")
+self.addrule("PKG_VERSION=filesystem|1.0-2")
+self.addrule("!FILE_PACSAVE=etc/profile")
+self.addrule("FILE_PACNEW=etc/profile")
+self.addrule("FILE_EXIST=etc/profile")