Fix installation of files

CHANGELOG.md

@@ -9,6 +9,7 @@
 - Fixed the building of wheels with C extensions and an `src` layout.
 - Fixed extras being selected when resolving dependencies even when not required.
 - Fixed performance issues when packaging projects if a lot of files were excluded.
+- Fixed installation of files.
 
 
 ## [0.12.6] - 2018-11-05

poetry/installation/pip_installer.py

@@ -126,7 +126,7 @@ class PipInstaller(BaseInstaller):
             else:
                 req = os.path.realpath(package.source_url)
 
-            if package.develop:
+            if package.develop and package.source_type == "directory":
                 req = ["-e", req]
 
             return req