On Windows 10 if Fetch, Pull,... are executed the command always ends with an fatal error:

a Quick google search says that on windows 10 cygwin can not fork a 32bit process from a 64bit process and vice versa.

log:

2 [main] sh 22684 C:\Users\XXX\AppData\Local\Atlassian\SourceTree\git_local\usr\bin\sh.exe: *** fatal error in forked process - fork: can't reserve memory for parent stack 0x5200000 - 0x5400000, (child has 0x5060000 - 0x5260000), Win32 error 487
1311 [main] sh 22684 cygwin_exception::open_stackdumpfile: Dumping stack trace to sh.exe.stackdump
3 [main] sh 25448 fork: child -1 - forked process 22684 died unexpectedly, retry 0, exit code 0x100, errno 11
.git/hooks/post-merge: fork: retry: Resource temporarily unavailable
1 [main] sh 21664 C:\Users\XXX\AppData\Local\Atlassian\SourceTree\git_local\usr\bin\sh.exe: *** fatal error in forked process - fork: can't reserve memory for parent stack 0x5200000 - 0x5400000, (child has 0x4C90000 - 0x4E90000), Win32 error 487
555 [main] sh 21664 cygwin_exception::open_stackdumpfile: Dumping stack trace to sh.exe.stackdump
1122312 [main] sh 25448 fork: child -1 - forked process 21664 died unexpectedly, retry 0, exit code 0x100, errno 11
.git/hooks/post-merge: fork: retry: Resource temporarily unavailable
1 [main] sh 24648 C:\Users\XXX\AppData\Local\Atlassian\SourceTree\git_local\usr\bin\sh.exe: *** fatal error in forked process - fork: can't reserve memory for parent stack 0x5200000 - 0x5400000, (child has 0x4A00000 - 0x4C00000), Win32 error 487
1815 [main] sh 24648 cygwin_exception::open_stackdumpfile: Dumping stack trace to sh.exe.stackdump
3206422 [main] sh 25448 fork: child -1 - forked process 24648 died unexpectedly, retry 0, exit code 0x100, errno 11
.git/hooks/post-merge: fork: retry: Resource temporarily unavailable
2 [main] sh 15640 C:\Users\XXX\AppData\Local\Atlassian\SourceTree\git_local\usr\bin\sh.exe: *** fatal error in forked process - fork: can't reserve memory for parent stack 0x5200000 - 0x5400000, (child has 0x4C00000 - 0x4E00000), Win32 error 487
894 [main] sh 15640 cygwin_exception::open_stackdumpfile: Dumping stack trace to sh.exe.stackdump
7281392 [main] sh 25448 fork: child -1 - forked process 15640 died unexpectedly, retry 0, exit code 0x100, errno 11
.git/hooks/post-merge: fork: retry: Resource temporarily unavailable