Trac #29240: Upgrade pexpect to 4.8

Requires changes to expect_upto and expect_peek due to [1]. Removed
patch merged upstream

[1] pexpect/pexpect@fa084459198f7e9f4a2f346ea8
bdac2ca102bc87

Tarball: https://codeload.github.com/pexpect/pexpect/tar.gz/4.8.0

URL: https://trac.sagemath.org/29240
Reported by: arojas
Ticket author(s): Antonio Rojas, Samuel Lelièvre
Reviewer(s): Matthias Koeppe

build/pkgs/pexpect/checksums.ini

@@ -1,4 +1,5 @@
 tarball=pexpect-VERSION.tar.gz
-sha1=3d79bb7de5436cd0a8417a6249c765595a33abcf
-md5=d4f3372965a996238d57d19b95d2e03a
-cksum=2052391001
+sha1=3f6c41a4a72dc802f3431f5d2367a4259f9b1813
+md5=b260eb284efc19489466b804ff53c59b
+cksum=966265148
+upstream_url=https://codeload.github.com/pexpect/pexpect/tar.gz/VERSION

build/pkgs/pexpect/package-version.txt

@@ -1 +1 @@
-4.6.0.p0
+4.8.0

src/sage/interfaces/sagespawn.pyx

@@ -149,7 +149,8 @@ class SageSpawn(spawn):
             u'hello world\r\n'
         """
         ret = self.expect(*args, **kwds)
-        self.buffer = self.before + self.after + self.buffer
+        self._before = self.buffer_type()
+        self._before.write(self.before + self.after + self.buffer)
         return ret
 
     def expect_upto(self, *args, **kwds):
@@ -167,7 +168,8 @@ class SageSpawn(spawn):
             u'world\r\n'
         """
         ret = self.expect(*args, **kwds)
-        self.buffer = self.after + self.buffer
+        self._before = self.buffer_type()
+        self._before.write(self.after + self.buffer)
         return ret