Protect against absent global IPython instance.

This basically applies most of the changes to ultraTB made by Brian in the
reorg branch here:

http://bazaar.launchpad.net/~ipython-dev/ipython/module-reorg/revision/1225

To our duplicate copies of ultraTB (the duplication is already gone in the
reorg branch).

This now means that the trial-based tests run fine if executed as

trial IPython

OR 

trial IPython.kernel

where as the latter form was failing before.  The reason why the former used
to work was that a hidden global ipython is created, *upon import*, by
ipdoctest.  That will stay for now, but I've made it bug

https://bugs.launchpad.net/ipython/+bug/409096

marked as critical for 0.11 that I'll need to fix.

IPython/kernel/core/ultraTB.py

@@ -267,9 +267,10 b' def _formatTracebackLines(lnum, index, lines, Colors, lvals=None,scheme=None):'
 
     # This lets us get fully syntax-highlighted tracebacks.
     if scheme is None:
-        try:
-            scheme = ipapi.get().IP.rc.colors
-        except:
+        ipinst = ipapi.get()
+        if ipinst is not None:
+            scheme = ipinst.IP.rc.colors
+        else:
             scheme = DEFAULT_SCHEME
     _line_format = _parser.format2
 
@@ -489,7 +490,9 b' class ListTB(TBTools):'
 
         # vds:>>
         if have_filedata:
-            ipapi.get().IP.hooks.synchronize_with_editor(filename, lineno, 0)
+            ipinst = ipapi.get()
+            if ipinst is not None:
+                ipinst.IP.hooks.synchronize_with_editor(filename, lineno, 0)
         # vds:<<
 
         return list
@@ -809,7 +812,9 b' class VerboseTB(TBTools):'
              filepath, lnum = records[-1][1:3]
              #print "file:", str(file), "linenb", str(lnum) # dbg
              filepath = os.path.abspath(filepath)
-             ipapi.get().IP.hooks.synchronize_with_editor(filepath, lnum, 0)
+             ipinst = ipapi.get()
+             if ipinst is not None:
+                 ipinst.IP.hooks.synchronize_with_editor(filepath, lnum, 0)
         # vds: <<
                 
         # return all our info assembled as a single string

IPython/ultraTB.py

@@ -267,9 +267,10 b' def _formatTracebackLines(lnum, index, lines, Colors, lvals=None,scheme=None):'
 
     # This lets us get fully syntax-highlighted tracebacks.
     if scheme is None:
-        try:
-            scheme = ipapi.get().IP.rc.colors
-        except:
+        ipinst = ipapi.get()
+        if ipinst is not None:
+            scheme = ipinst.IP.rc.colors
+        else:
             scheme = DEFAULT_SCHEME
     _line_format = _parser.format2
 
@@ -489,7 +490,9 b' class ListTB(TBTools):'
 
         # vds:>>
         if have_filedata:
-            ipapi.get().IP.hooks.synchronize_with_editor(filename, lineno, 0)
+            ipinst = ipapi.get()
+            if ipinst is not None:
+                ipinst.IP.hooks.synchronize_with_editor(filename, lineno, 0)
         # vds:<<
 
         return list
@@ -809,7 +812,9 b' class VerboseTB(TBTools):'
              filepath, lnum = records[-1][1:3]
              #print "file:", str(file), "linenb", str(lnum) # dbg
              filepath = os.path.abspath(filepath)
-             ipapi.get().IP.hooks.synchronize_with_editor(filepath, lnum, 0)
+             ipinst = ipapi.get()
+             if ipinst is not None:
+                 ipinst.IP.hooks.synchronize_with_editor(filepath, lnum, 0)
         # vds: <<
                 
         # return all our info assembled as a single string