conan: [bug] scm Attribute fails to clone commit

I feel like this is very related to https://github.com/conan-io/conan/issues/5587 “scm Attribute fails to clone tag” but in our case we are using version 1.19.2. which according to the note in #5587 “Conan 1.18.1 has been released with the fix for this issue!” should contain the fix.

Our old conanfile that worked in v1.16.1 did:

    scm = {"type": "git",
           "url": url,  # location of source to build
           "revision": commitAtVersion}

But now after upgrading to v1.19.2 it failed to check out any sources on our build servers. But if we comment out the scm section and add:

    # Testing: don't use scm in case it's broken https://github.com/conan-io/conan/issues/5587
    def source(self):
        git = tools.Git()
        os.remove("debian/changelog")
        #git.clone(self.url, branch=self.commitAtVersion)
        git.clone(self.url, branch="master")
        git.checkout(self.commitAtVersion)

then it works also in v1.19.2

Our commitAtVersion was a git commit string of the form e.g. 8aa1740b

Environment Details (include every applicable attribute)

• Operating System+version: Windows Server 2012 R2
• Compiler+version: VS2015
• Conan version: 1.19.2
• Python version: N/A conan exe installer

Steps to reproduce (Include if Applicable)

Update code from 1.16 to 1.19 and rebuild an existing recipe that uses the scm plugin while requesting a specific git commit.

Logs (Executed commands with output) (Include/Attach if Applicable)

(Sadly) silent fail of the git clone to actually check out any files, build fails shortly afterwards as it can’t find required .sln file to build:

pal/1.41.0@PORT/stable: Configuring sources in E:\nX\nX_nightlybuild\workspace\Conan_pipeline\.co\14e36c\1
pal/1.41.0@PORT/stable: Getting sources from url: 'git@bbgithub.dev.bloomberg.com:nx/pal.git'
[...]
The following files were specified on the command line:
	vstudio/pal/pal.sln
These files could not be found and will not be loaded.Microsoft (R) Build Engine version 14.0.25420.1