Fix conflicting file created during alr install

src/alire/alire-install.adb

@@ -49,9 +49,15 @@ package body Alire.Install is
          --  Use or regular deployment facilities, in case there are any
          --  actions to perform.
 
-         Rel.Deploy (Env           => Platforms.Current.Properties,
-                     Parent_Folder => Prefix,
-                     Was_There     => Was_There);
+         Rel.Deploy (Env             => Platforms.Current.Properties,
+                     Parent_Folder   => Prefix,
+                     Was_There       => Was_There,
+                     Mark_Completion => False);
+         --  We set Mark_Completion to False because the deployment folder
+         --  is temporary, so we don't need to track completion if the
+         --  installation fails, and otherwise we will have a common file to
+         --  all installations (the ./alire/ canary file) that will cause a
+         --  clash after the first installation.
 
          if not Rel.Project_Files (Platforms.Current.Properties,
                                    With_Path => False).Is_Empty

src/alire/alire-releases.adb

@@ -247,7 +247,8 @@ package body Alire.Releases is
       Was_There       : out Boolean;
       Perform_Actions : Boolean := True;
       Create_Manifest : Boolean := False;
-      Include_Origin  : Boolean := False)
+      Include_Origin  : Boolean := False;
+      Mark_Completion : Boolean := True)
    is
       use Alire.Directories;
       use all type Alire.Properties.Actions.Moments;
@@ -350,7 +351,9 @@ package body Alire.Releases is
          end;
       end if;
 
-      Completed.Mark (Complete => True);
+      if Mark_Completion then
+         Completed.Mark (Complete => True);
+      end if;
 
    exception
       when E : others =>

src/alire/alire-releases.ads

@@ -348,11 +348,15 @@ package Alire.Releases is
       Was_There       : out Boolean;
       Perform_Actions : Boolean := True;
       Create_Manifest : Boolean := False;
-      Include_Origin  : Boolean := False);
+      Include_Origin  : Boolean := False;
+      Mark_Completion : Boolean := True);
    --  Deploy the sources of this release under the given Parent_Folder. If
    --  Create_Manifest, any packaged manifest will be moved out of the way
    --  and an authoritative manifest will be generated from index information.
-   --  The created manifest may optionally Include_Origin information.
+   --  The created manifest may optionally Include_Origin information. When
+   --  Mark_Completion, a trace file will be created in ./alire/copy_complete
+   --  so future inspections of the folder can ensure the operation wasn't
+   --  interrupted.
 
 private
 

testsuite/tests/install/independent/my_index/index/cr/crate1/crate1-1.0.0.toml

@@ -0,0 +1,10 @@
+description = "Sample crate"
+name = "crate1"
+version = "1.0.0"
+licenses = []
+maintainers = ["[email protected]"]
+maintainers-logins = ["someone"]
+
+[origin."case(os)"."..."]
+url = "file:../../../crates/crate/crate1.tgz"
+hashes = ["sha256:d35efed8325f646652f533fa4094d580cf28bccc9cc1d85751738b446bbed37a"]

testsuite/tests/install/independent/my_index/index/cr/crate2/crate2-1.0.0.toml

@@ -0,0 +1,10 @@
+description = "Sample crate"
+name = "crate2"
+version = "1.0.0"
+licenses = []
+maintainers = ["[email protected]"]
+maintainers-logins = ["someone"]
+
+[origin."case(os)"."..."]
+url = "file:../../../crates/crate/crate2.tgz"
+hashes = ["sha256:8a814f2f0683b3b4db10a1c1e08e951d81de0deff2fa0f70a29295e45184b795"]

testsuite/tests/install/independent/my_index/index/index.toml

@@ -0,0 +1 @@
+version = "1.2"

testsuite/tests/install/independent/test.py

@@ -0,0 +1,23 @@
+"""
+Test installation of two independent crates with `alr install` to verify that
+our deployment system doesn't introduce any conflicts.
+"""
+
+from drivers.alr import run_alr, init_local_crate
+from drivers.asserts import assert_eq, assert_match, assert_installed
+from subprocess import run
+
+import os
+
+
+PREFIX=os.path.join(os.getcwd(), "install")
+PREFIX_ARG=f"--prefix={PREFIX}"
+
+# Install both crates one after the other, shouldn't fail
+run_alr("install", PREFIX_ARG, "crate1")
+run_alr("install", PREFIX_ARG, "crate2")
+
+# Check contents of the prefix
+assert_installed(PREFIX, ["crate1=1.0.0", "crate2=1.0.0"])
+
+print('SUCCESS')

testsuite/tests/install/independent/test.yaml

@@ -0,0 +1,4 @@
+driver: python-script
+indexes:
+    my_index:
+        in_fixtures: false