TEAM Engine REST interface creates sessions which might run to a maximum

[dstenger]

Describe the bug
TEAM Engine REST interface creates session files in ${USER}/rest/ folder.
The naming is limited to the range of s0000 to s9999.
After the upper limit is reached, tests executed via REST interface might fail (HTTP status code of execution is 500).

To Reproduce
Steps to reproduce the behavior:

1. Set up TEAM Engine with user which contains sessions in the range of s0000 to s9999 in rest/ folder.
2. Execute test run via REST interface (also try parallel runs of multiple test suites).
3. Test run exits with HTTP status code 500.
4. Beware, the error is not reproducible with all test suites. I was able to reproduce it with ets-wmts10, ets-wcs20, ets-wms13, and ets-wms11.

Expected behavior
The unexpected error does not occur anymore (HTTP status code 500).
Possible solutions:

• Engine clears rest folder automatically.
• User or administrator is informed.

Additional context
The problem might also occur with sessions created via Web Browser Interface (folder ${USER}/).

[dstenger]

First step might be to check why the sessions are created in ${USER}/rest/ folder and how they can be accessed.