Solution : https://service.sap.com/sap/support/notes/739086 (SAP Service marketplace login required)
Key words : 
import parameters 'revno', tab title 'import', table parameter 'textcopy', incomplete change documents, 'me_get_requisition_text_ext' function module, 'me_create_requisition_ext' function module, text change documents, solution item texts, change documents, function builder
Related Notes : 
       
| 1447078 | IW32: Update termination in FM MEDCM_UPDATE_REVISION | 
| 874748 | Lang sel when copying long text to an ext created PReq | 
| 874286 | External changes to long texts disappear in PReq | 
| 851485 | Delete long text not copied into PReq |