Solution : https://service.sap.com/sap/support/notes/1071731 (SAP Service marketplace login required)
Key words : 
shell commands produce utf-8 output, utf-8 operating system locale, calling operating system commands, accessing national special characters, national special characters, command line parameters, -7-bit-ascii characters, symptom unicode kernel, expected unicode encoding, proper unicode encoding
Related Notes : 
       
| 1319517 | Unicode Collection Note | 
| 1048674 | core in Unicode UTF-8 environment scan | 
| 1036341 | Unicode executables and corrupt UTF-8 in input files | 
| 966645 | Unicode executables and corrupt UTF-8 in call or environment | 
| 752835 | Usage of the file interfaces in Unicode systems | 
| 11682 | Compiling RFC programs |