conan: [bug] conan export then conan install does not update sources

Environment Details (include every applicable attribute)

• Operating System+version: Any
• Compiler+version: Any
• Conan version: 1.19.2
• Python version: 3.7

Steps to reproduce (Include if Applicable)

On our ci server, we have the following workflow.

$ conan export alex/dev /path/to/dep1
$ conan install /path/to/app/conanfile.txt --update --install-folder=/path/to/install_dir --build missing

the conanfile contains the reference to dep1/dev@alex/dev.

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

conan export /path/to/dep1 alex/dev
Exporting package recipe
dep1/dev@tanker/dev exports_sources: Copied 34 '.txt' files
//... all sources are being copied
**dep1/dev@tanker/dev: The stored package has not changed**
dep1/dev@tanker/dev: Using the exported files summary hash as the recipe revision: aee801aab70f4f4d6d4c1bec690c700e 
dep1/dev@tanker/dev: Exported revision: aee801aab70f4f4d6d4c1bec690c700e

Then the build called by conan install fails for the dep1, because the sources are not up-to-date. The exported source seems not be used. The updated sources are in the export_source folder but conan uses the sources from the source folder.

We do exports_sources = "*" in the dep1’s conanfile.py. We don’t know where the source folder comes from.

Our current workaround is to conan remove the dep1/dev@alex/dev on the CI server, which is pretty annoying.