if the extra source/test paths added via build-helper plugin are specified as paths under the module dir (i.e. no ".." are used in path), then the project can be opened by IDEA, but the path is not resolved anyway.
For example see the following snippet:
<configuration> <sources> <source>sources_to_add/src</source> <!--source>../../sources_to_add/src</source--> <!--cannot be opened - see 24337--> </sources> </configuration>
for the commented out path - IDEA-42506;
for the not commented one the project is normally created, but the extra path is added to module incorrectly:
in iml file:
<content url="file://sources_to_add/src">
<sourceFolder url="file://sources_to_add/src" isTestSource="false" />
</content>



Issue was resolved