strip: simplify some repeated conditions

strip: simplify some repeated conditions

We check "if saveheads or savebases" in several places to see if we
should or have created a bundle of the changesets to apply after
truncating the revlogs. One of the conditions is actually just "if
saveheads", but since there can't be savebases without saveheads, that
is effectively the same condition. It seems simpler to check only once
and from then on see if we created the file.

--- a/mercurial/repair.py	Mon Aug 29 07:07:15 2016 +0200
+++ b/mercurial/repair.py	Thu Sep 15 10:18:56 2016 -0700
@@ -147,7 +147,8 @@
                        vfs.join(backupfile))
         repo.ui.log("backupbundle", "saved backup bundle to %s\n",
                     vfs.join(backupfile))
-    if saveheads or savebases:
+    chgrpfile = None
+    if saveheads:
         # do not compress partial bundle if we remove it from disk later
         chgrpfile = _bundle(repo, savebases, saveheads, node, 'temp',
                             compress=False)
@@ -184,7 +185,7 @@
                 if troffset == 0:
                     repo.store.markremoved(file)
 
-        if saveheads or savebases:
+        if chgrpfile:
             ui.note(_("adding branch\n"))
             f = vfs.open(chgrpfile, "rb")
             gen = exchange.readbundle(ui, f, chgrpfile, vfs)
@@ -229,12 +230,12 @@
         if backupfile:
             ui.warn(_("strip failed, full bundle stored in '%s'\n")
                     % vfs.join(backupfile))
-        elif saveheads:
+        elif chgrpfile:
             ui.warn(_("strip failed, partial bundle stored in '%s'\n")
                     % vfs.join(chgrpfile))
         raise
     else:
-        if saveheads or savebases:
+        if chgrpfile:
             # Remove partial backup only if there were no exceptions
             vfs.unlink(chgrpfile)