bitbake: bb.fetch2.{git, hg}: remove tarball if it needs updating

We were maintaining state in the form of ud.repochanged to determine whether
we need to write the tarball in the case where the tarball already exists, but
this state is maintained only in memory. If we need to update the git repo,
set ud.repochanged to True, and then are interrupted or killed, the tarball
will then be out of date.

Rather than maintaining this state, simply remove the out of date tarball when
we update the git repo, and it will be re-created with updated content in
build_mirror_data.

[YOCTO #6366]

(Bitbake rev: eaaa81393f181432c8586b17ade623f42c9fed2e)

Signed-off-by: Christopher Larson <chris_larson@mentor.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/bb/fetch2/git.py

@@ -181,8 +181,6 @@ class Git(FetchMethod):
     def download(self, ud, d):
         """Fetch url"""
 
-        ud.repochanged = not os.path.exists(ud.fullmirror)
-
         # If the checkout doesn't exist and the mirror tarball does, extract it
         if not os.path.exists(ud.clonedir) and os.path.exists(ud.fullmirror):
             bb.utils.mkdirhier(ud.clonedir)
@@ -220,7 +218,11 @@ class Git(FetchMethod):
             runfetchcmd(fetch_cmd, d)
             runfetchcmd("%s prune-packed" % ud.basecmd, d)
             runfetchcmd("%s pack-redundant --all | xargs -r rm" % ud.basecmd, d)
-            ud.repochanged = True
+            try:
+                os.unlink(ud.fullmirror)
+            except OSError as exc:
+                if exc.errno != errno.ENOENT:
+                    raise
         os.chdir(ud.clonedir)
         for name in ud.names:
             if not self._contains_ref(ud, d, name):
@@ -228,7 +230,7 @@ class Git(FetchMethod):
 
     def build_mirror_data(self, ud, d):
         # Generate a mirror tarball if needed
-        if ud.write_tarballs and (ud.repochanged or not os.path.exists(ud.fullmirror)):
+        if ud.write_tarballs and not os.path.exists(ud.fullmirror):
             # it's possible that this symlink points to read-only filesystem with PREMIRROR
             if os.path.islink(ud.fullmirror):
                 os.unlink(ud.fullmirror)