trydiff: join elements in 'header' list by '\n'

trydiff: join elements in 'header' list by '\n'

It seems natural that each element in the list corresponds to one line
of output. That is currently true, but only because each element in
the list has a trailing newline. Let's drop those newlines and instead
add them when we print the headers.

--- a/mercurial/patch.py	Fri Jan 16 15:27:04 2015 -0800
+++ b/mercurial/patch.py	Fri Jan 16 15:34:03 2015 -0800
@@ -1755,7 +1755,7 @@
 
     def diffline(f, revs):
         revinfo = ' '.join(["-r %s" % rev for rev in revs])
-        return 'diff %s %s\n' % (revinfo, f)
+        return 'diff %s %s' % (revinfo, f)
 
     date1 = util.datestr(ctx1.date())
     date2 = util.datestr(ctx2.date())
@@ -1836,34 +1836,34 @@
         path2 = posixpath.join(prefix, f2)
         header = []
         if opts.git:
-            header.append('diff --git %s%s %s%s\n' %
+            header.append('diff --git %s%s %s%s' %
                           (aprefix, path1, bprefix, path2))
             if content1 is None: # added
-                header.append('new file mode %s\n' % gitmode[flag2])
+                header.append('new file mode %s' % gitmode[flag2])
             elif content2 is None: # removed
-                header.append('deleted file mode %s\n' % gitmode[flag1])
+                header.append('deleted file mode %s' % gitmode[flag1])
             else:  # modified/copied/renamed
                 mode1, mode2 = gitmode[flag1], gitmode[flag2]
                 if mode1 != mode2:
-                    header.append('old mode %s\n' % mode1)
-                    header.append('new mode %s\n' % mode2)
+                    header.append('old mode %s' % mode1)
+                    header.append('new mode %s' % mode2)
                 if op is not None:
-                    header.append('%s from %s\n' % (op, path1))
-                    header.append('%s to %s\n' % (op, path2))
+                    header.append('%s from %s' % (op, path1))
+                    header.append('%s to %s' % (op, path2))
         elif revs and not repo.ui.quiet:
             header.append(diffline(path1, revs))
 
         if binarydiff and not opts.nobinary:
             text = mdiff.b85diff(content1, content2)
             if text and opts.git:
-                header.append('index %s..%s\n' %
+                header.append('index %s..%s' %
                               (gitindex(content1), gitindex(content2)))
         else:
             text = mdiff.unidiff(content1, date1,
                                  content2, date2,
                                  path1, path2, opts=opts)
         if header and (text or len(header) > 1):
-            yield ''.join(header)
+            yield '\n'.join(header) + '\n'
         if text:
             yield text