pcc/ninja — comment on commit ff9cc51b9e52f7ae8c3de0ea1cc3df2123e78553
File: src/build_test.cc line 195
By pcc:

Right. Builder thinks it owns its CommandRunner, so we need to release its ownership to prevent a double free. (We could introduce a new object to act as the CommandRunner in this instance but I think that this will do for a test.)