diff -up yum-3.4.3/docs/yum.conf.5.orig yum-3.4.3/docs/yum.conf.5

--- yum-3.4.3/docs/yum.conf.5.orig	2016-08-02 15:08:10.160947580 +0200

+++ yum-3.4.3/docs/yum.conf.5	2016-08-02 15:08:30.046853379 +0200

@@ -381,6 +381,13 @@ that Yum does. This option can take the

 `packages' means that only RPM package downloads should be cached (but not

 repository metadata downloads).

+`lazy:packages' means that act like `packages' unless package verification

+fails (e.g. the package download doesn't match the expected checksum), in which

+case try re-downloading the package as if `none' was set.  This value is a good

+compromise if you want to avoid issues caused by stale proxy cache after remote

+RPMs change contents without changing filenames (e.g. are pushed unsigned and

+later signed) but still want the benefits of package caching whenever possible.

+

 `none' means that no HTTP downloads should be cached.

 The default is `all'. This is recommended unless you are experiencing caching

diff -up yum-3.4.3/output.py.orig yum-3.4.3/output.py

--- yum-3.4.3/output.py.orig	2016-08-02 15:08:10.074947988 +0200

+++ yum-3.4.3/output.py	2016-08-02 15:08:30.053853346 +0200

@@ -472,6 +472,13 @@ class YumOutput:

         :raises: *errobj*.exception

         """

         self.logger.error('%s: %s', errobj.url, errobj.exception)

+        if hasattr(errobj, 'retry_no_cache') and errobj.retry_no_cache and \

+                errobj.exception.errno < 0:

+            self.logger.error(_('Trying again, now avoiding proxy cache.'))

+            # Raising an exception would cause urlgrabber to jump to the next

+            # mirror and what we want here is to retry with the same, so just

+            # return.

+            return

         self.logger.error(_('Trying other mirror.'))

         self.suggestKBaseArticle(errobj)

         raise errobj.exception

diff -up yum-3.4.3/yum/config.py.orig yum-3.4.3/yum/config.py

--- yum-3.4.3/yum/config.py.orig	2016-08-02 15:08:10.159947585 +0200

+++ yum-3.4.3/yum/config.py	2016-08-02 15:08:30.048853370 +0200

@@ -810,7 +810,8 @@ class YumConf(StartupConf):

     deltarpm_percentage = IntOption(75, range_min=0, range_max=100)

     deltarpm_metadata_percentage = IntOption(100, range_min=0)

-    http_caching = SelectionOption('all', ('none', 'packages', 'all'))

+    http_caching = SelectionOption('all', ('none', 'packages', 'all',

+                                           'lazy:packages'))

     metadata_expire = SecondsOption(60 * 60 * 6) # Time in seconds (6h).

     metadata_expire_filter = SelectionOption('read-only:present',

                                              ('never', 'read-only:future',

diff -up yum-3.4.3/yum/__init__.py.orig yum-3.4.3/yum/__init__.py

diff -up yum-3.4.3/yum.spec.orig yum-3.4.3/yum.spec

--- yum-3.4.3/yum.spec.orig	2016-08-02 15:08:10.150947628 +0200

+++ yum-3.4.3/yum.spec	2016-08-02 15:08:30.047853374 +0200

@@ -63,7 +63,7 @@ BuildRequires: python >= 2.4

 BuildRequires: rpm-python, rpm >= 0:4.4.2

 BuildRequires: python-iniparse

 BuildRequires: python-sqlite

-BuildRequires: python-urlgrabber >= 3.9.0-8

+BuildRequires: python-urlgrabber >= 3.10-8

 BuildRequires: yum-metadata-parser >= 1.1.0

 BuildRequires: pygpgme

 # End of CheckRequires

@@ -72,7 +72,7 @@ Requires: python >= 2.4

 Requires: rpm-python, rpm >= 0:4.4.2

 Requires: python-iniparse

 Requires: python-sqlite

-Requires: python-urlgrabber >= 3.9.0-8

+Requires: python-urlgrabber >= 3.10-8

 Requires: yum-metadata-parser >= 1.1.0

 Requires: pygpgme

 # rawhide is >= 0.5.3-7.fc18 ... as this is added.

diff -up yum-3.4.3/yum/yumRepo.py.orig yum-3.4.3/yum/yumRepo.py

--- yum-3.4.3/yum/yumRepo.py.orig	2016-08-02 15:08:10.104947846 +0200

+++ yum-3.4.3/yum/yumRepo.py	2016-08-02 15:08:30.052853351 +0200

@@ -336,6 +336,7 @@ class YumRepository(Repository, config.R

         self._repoXML = None

         self._oldRepoMDData = {}

         self.cache = 0

+        self._retry_no_cache = False

         self.mirrorlistparsed = 0

         self.yumvar = {} # empty dict of yumvariables for $string replacement

         self._proxy_dict = {}

@@ -993,6 +994,7 @@ Insufficient space in download directory

                             interrupt_callback=self.interrupt_callback,

                             checkfunc=checkfunc,

                             size=size,

+                            retry_no_cache=self._retry_no_cache,

                             **ugopts)

             remote = url + '/' + relative

@@ -1020,6 +1022,7 @@ Insufficient space in download directory

                                            checkfunc=checkfunc,

                                            http_headers=headers,

                                            size=size,

+                                           retry_no_cache=self._retry_no_cache,

                                            **kwargs

                                            )

             except URLGrabError, e:

@@ -1049,15 +1052,22 @@ Insufficient space in download directory

                     misc.unlink_f(local)

                     raise URLGrabError(-1, _('Package does not match intended download.'))

-        ret = self._getFile(url=basepath,

-                        relative=remote,

-                        local=local,

-                        checkfunc=checkfunc,

-                        text=text,

-                        cache=cache,

-                        size=package.size,

-                        **kwargs

-                        )

+        # We would normally pass this to _getFile() directly but that could

+        # break backward compatibility with plugins that override _getFile()

+        # (BZ 1360532).

+        self._retry_no_cache = self.http_caching == 'lazy:packages'

+        try:

+            ret = self._getFile(url=basepath,

+                            relative=remote,

+                            local=local,

+                            checkfunc=checkfunc,

+                            text=text,

+                            cache=cache,

+                            size=package.size,

+                            **kwargs

+                            )

+        finally:

+            self._retry_no_cache = False

         if not kwargs.get('async') and not package.verifyLocalPkg():

             # Don't return as "success" when bad.