doClip:empty path error caused by line in CPPlotSymbol.m, with fix

What steps will reproduce the problem?
1. define a CGMutablePathRef with a single circle (using CGPathAddArc)
2. assign this path as a custom CPPlotSymbol for a plot
3. run the app

What is the expected output? What do you see instead?

- Expected output: no error.

- A 'doClip:empty path' error appears in XCode's debug 
window each time it tries to draw the symbol.  However, the symbol appears 
nonetheless. The only issue is the nonfatal error message.

What version of the product are you using? On what operating system?

CP 0.3 on iOS.

Please provide any additional information below.

The error is caused by this line in CPPlotSymbol.m:

                    CGContextClip(theContext);

The error can be fixed by replacing this line with the following code:

                    if ( !CGPathIsEmpty(theSymbolPath) ) {
                        CGContextClip(theContext);
                    }

Original issue reported on code.google.com by daa...@gmail.com on 17 Jun 2011 at 8:04

gujjula / core-plot

doClip:empty path error caused by line in CPPlotSymbol.m, with fix #293