fix exec path on the mac for project files in which the

exec path is not specified, by testing whether the
string is empty before calling SetProject, because
SetProject replaces the empty string by the
project path

CleanIDE/Pm/PmProject.icl

@@ -836,18 +836,19 @@ ReadProjectFile projectPath applicationDir ps
 		=	((emptyProject,False,"The file \"" +++  projectName +++ "\" is an old project and could not be opened."),ps)
 	#!	(options, file)			= ReadOptionsFile file
 		projectGO				= GetProject applicationDir projectDir emptyProject
-		project					= GetOptions ProjectTable options projectGO
-		project					= (if (version == "1.3")
+		projectGO				= GetOptions ProjectTable options projectGO
+		projectGO				= (if (version == "1.3")
 									(\p->{p&pg_target="StdEnv"})
 									(id)
-								) project	// DvA: need to set needs save flag for project;
+								) projectGO	// DvA: need to set needs save flag for project;
 /*
 It's better to replace above with a dialog with popup of available environments.
 */
-		project					= SetProject applicationDir projectDir project
+		unexpanded_exec_path	= projectGO.pg_execpath
+		project					= SetProject applicationDir projectDir projectGO
 		execpath				= PR_GetExecPath project
 		(rootpath,project)		= PR_GetRootPathName project
-		project					= PR_SetExecPath (if (execpath=="") (MakeExecPathname rootpath) execpath) project
+		project					= PR_SetExecPath (if (size unexpanded_exec_path==0) (MakeExecPathname rootpath) execpath) project
 		(closed, ps)			= fclose file ps
 	| not closed
 		// generate warning?