Note: commenting out "gost" engine had no effect. Commenting out "pkcs11" engine completely resolved this problem, but caused a different problem with an app that uses OpenSSL and libp11 to access smartcards.
Here's the hanging process snap, in case it can help figuring what's wrong:
Sampling process 31833 for 3 seconds with 1 millisecond of run time between samples
Sampling completed, processing symbols...
Analysis of sampling git-remote-https (pid 31833) every 1 millisecond
Process: git-remote-https 
Load Address: 0x103bb3000
Code Type: X86-64
Parent Process: git 
Date/Time: 2019-07-23 18:28:11.777 -0400
Launch Time: 2019-07-23 18:27:35.376 -0400
OS Version: Mac OS X 10.14.6 (18G84)
Report Version: 7
Analysis Tool: /usr/bin/sample