add run_pager() and make osc log/diff work like git log/diff

Added new function run_pager() to get 'osc log/diff' work like
'git log/diff' which send the output to PAGER (which is by default:
less or what's defined in the environment).

Signed-off-by: Danny Kukawka <danny.kukawka@web.de>

osc/commandline.py

@@ -1894,7 +1894,7 @@ Please submit there instead, or use --nodevelproject to force direct submission.
                 diff += server_diff(pac.apiurl, pac.prjname, pac.name, rev1,
                                     pac.prjname, pac.name, rev2, not opts.plain, opts.missingok)
         if len(diff) > 0:
-            print diff
+            run_pager(diff)
 
 
     @cmdln.option('--oldprj', metavar='OLDPRJ',
@@ -3699,7 +3699,8 @@ Please submit there instead, or use --nodevelproject to force direct submission.
         if opts.xml:
             format = 'xml'
 
-        print '\n'.join(get_commitlog(apiurl, project, package, rev, format))
+        log = '\n'.join(get_commitlog(apiurl, project, package, rev, format))        
+        run_pager(log)
 
     @cmdln.option('-f', '--failed', action='store_true',
                   help='rebuild all failed packages')

osc/core.py

@@ -2480,6 +2480,23 @@ def read_meta_from_spec(specfile, *args):
 
     return spec_data
 
+def run_pager(message):
+        import tempfile
+
+        tmpfile = None
+
+        if tmpfile is None:
+            tmpfile = tempfile.NamedTemporaryFile()
+
+        tmpfile.write(message)
+        tmpfile.flush()
+        pager = os.getenv('PAGER', default='less')
+        subprocess.call('%s %s' % (pager, tmpfile.name), shell=True)
+
+        if tmpfile is not None:
+            tmpfile.close()
+
+
 def run_editor(filename):
     if sys.platform[:3] != 'win':
         editor = os.getenv('EDITOR', default='vim')