on debug builds, set versionCode using DB_VERSION + commit count

This provides an automatic way to generate updates from each new debug
build, it is build from the developer's machine or via the nightly repo.

app/build.gradle

@@ -237,6 +237,32 @@ android {
         }
     }
 
+    /* set the debug versionCode based on DB verson and how many commits in the repo */
+    applicationVariants.all { variant ->
+        if (variant.buildType.isDebuggable()) {
+            // default to a timestamp, in case anything fails later
+            variant.mergedFlavor.versionCode = new Date().getTime() / 1000
+            try {
+                def stdout = new ByteArrayOutputStream()
+                exec {
+                    commandLine 'git', 'rev-list', '--first-parent', '--count', 'HEAD'
+                    standardOutput = stdout
+                }
+                def commitCount = Integer.parseInt(stdout.toString().trim())
+                stdout = new ByteArrayOutputStream()
+                exec {
+                    commandLine 'sed', '-n', 's,.*DB_VERSION *= *\\([0-9][0-9]*\\).*,\\1,p', 'src/main/java/org/fdroid/fdroid/data/DBHelper.java'
+                    standardOutput = stdout
+                }
+                def dbVersion = Integer.parseInt(stdout.toString().trim())
+                println 'Setting debug versionCode: ' + sprintf("%d%05d", [dbVersion, commitCount])
+                variant.mergedFlavor.versionCode = Integer.parseInt(sprintf("%d%05d", [dbVersion, commitCount]))
+            }
+            catch (ignored) {
+            }
+        }
+    }
+
     testOptions {
         unitTests {
             // prevent tests from dying on android.util.Log calls

config/nightly-repo/deploy

@@ -9,10 +9,6 @@ apt-get update
 apt-get install -y --no-install-recommends -t stretch-backports \
         fdroidserver openssh-client rsync python3-qrcode
 
-db=`sed -n 's,.*DB_VERSION *= *\([0-9][0-9]*\).*,\1,p' app/src/main/java/org/fdroid/fdroid/data/DBHelper.java`
-count=`git rev-list --first-parent --count HEAD`
-sed -i "s,versionCode *[0-9][0-9]*.*,versionCode `printf '%d%05d' $db $count`," app/build.gradle
-
 repo_git_base=${CI_PROJECT_NAMESPACE}/${CI_PROJECT_NAME}-nightly
 repo_base=https://gitlab.com/${repo_git_base}
 repo_url=${repo_base}/raw/master/fdroid/repo