runtime/6626217/Test6626217.sh does the following:

1. copies java files (including many_loader.java and bug_21227.java) to the work dir
2. compiles them
3. substitutes many_loader.java with another version
4. compiles new version of many_loader.java

The problem occures when bug_21227.java and bug_21227.class have the same timestamp (i.e. steps 1 and 2 happened within 1 second). In this case, during step 4, the recompilation of bug_21227.java is triggered; it fails with the following message:

java version "1.7.0-ea"
Java(TM) SE Runtime Environment (build 1.7.0-ea-b124)
Java HotSpot(TM) Server VM (build 20.0-b05, mixed mode)
warning: [options] bootstrap class path not set in conjunction with -source 1.4
1 warning
warning: [options] bootstrap class path not set in conjunction with -source 1.4
./bug_21227.java:40: warning: [static] static variable should be qualified by type name, bug_21227, instead of by an expression
    You_Have_Been_P0wned q = b._p0wnee;
                              ^
./bug_21227.java:40: incompatible types
    You_Have_Been_P0wned q = b._p0wnee;
                              ^
  required: You_Have_Been_P0wned
  found: Object
1 error
2 warnings
mv: cannot access many_loader.class
result: Failed. Execution failed: exit code 1